15 years have passed since the pioneering publication of R.Z.Valiev and co-authors [1] who showed that plastic deformation under enhanced hydrostatic pressure can achieve nanostructures in bulk materials. While the first years have shown highlights in mechanical properties i.e. high strength paired with considerable ductility, as well as superplasticity at high deformation rates [2], recent research activities increasingly present outstanding SPD- functional nanomaterials [3]. Those exhibit advances in radiation damage resistance, electrical conductivity, hydrogen storage and especially thermoelectricity where even world records in both p- and n-type semiconductors were broken [4]. Very recent findings in SPD-processed magnetic and biodegradable nanomaterials prove that for functional properties low-dimensional SPD-induced lattice defects like dislocations and vacancy loops are more beneficial than high-dimensional ones like grain- or phase boundaries [4].
[1] R.Z. Valiev, I. Alexandrov, R. Islamgaliev, Bulk nanostructured materials from severe plastic deformation, Progr.Mater.Sci. 45, 103-189 (2000)
[2] M. Zehetbauer, Y.T. Zhu (eds.) Bulk nanostructured materials, 2009 WILEY-VCH Verlag GmbH & Co, Weinheim, Germany
[3] M. Zehetbauer, R. Groessinger, H. Krenn, M. Krystian, R. Pippan, P. Rogl, T. Waitz, R. Wuerschum, Bulk Nanostructured Functional Materials by Severe Plastic Deformation, Adv.Eng.Mater. 12, 692-700 (2010)
[4] R. Z. Valiev, Y. Estrin, Z. Horita, T. G. Langdon, M. J. Zehetbauer, Y. T. Zhu, Fundamentals of Superior Properties in Bulk NanoSPD Materials, Mater.Res.Lett. 4, 1-21 (2016)

We have developed a new analysis system for identifying the orientation of icosahedral quasicrystal (iQc) in a SEM installed with an electron back scattering diffraction (EBSD) instrument. The system has been successful in assigning the orientations of the iQc and a ��Mg phases in a eutectic structure prepared by a unidirectional solidification process at a different cooling rate in the Mg-Cd-Yb system. A regular rod-like microstructure was observed in wide regions, where inter-rod spacing decreases with increasing solidification rate. Significant contributions of unidirectional solidification on microstructure were confirmed. It is clear that basal plane of Mg and 2-fold symmetry plane of QC reveal the similar lattice spacing. Also, the prismatic plane of Mg and 5-fold symmetry plane of iQC have the similar lattice spacing. According to EBSD result, the growth direction of iQC/Mg eutectic structure is �q 2f �r_QC // �q 1 0 1 ̅ 0 �r_Mg and a unique orientation relationships between iQC and Mg have been verified. The similar lattice spacing with planar normal along growth direction is a key factor stabilizing the interface of iQC and Mg. In the unidirectional solidification samples, the eutectic growth of iQC/Mg is analyzed to be a non-facet/non-facet mode.

We demonstrate thin film Cu-Ni-M alloys deposited directly on silicon, without a designated barrier, showing very high thermal stability at the temperature up to 700�� for 1h. Here M is an element insoluble with Cu but soluble with Ni. Thin [M-Ni12]Cux films were sputter deposited, annealed and their materials and electrical properties were studied. The results can be explained by the ��cluster-plus-glue atom�� model for stable solid solutions, where [M-Ni12] cuboctahedral clusters are embedded in a Cu matrix. In this model, the clusters are congruent with the Cu minimizing atomic interactions allowing a good stability. The properties of the films were found to be affected by the M/Ni ratios. Especially, the (M1/13-Ni12/13)0.3Cu99.7 film had the lowest electrical resistivity below 3�I���cm. And even after 40h annealing at 500�� they maintained a low resistivity still below 3 �I���cm, demonstrating extremely high stabilities against silicide formation.

The failure of Drum & Economizer tubes of a boiler in Kazeroon Power plant occurred in 2015. An analysis of the failure was made by chemical and metallographic examinations and SEM studies. According to inspections, there were numerous small pits in fractured sections and inside surfaces of the failed tubes resembled orange peel which is a representative of Flow Accelerated Corrosion (FAC). The water chemistry of the boiler was examined and investigations revealed that water treatment was performed by the All Volatile Treatment method in which dissolved oxygen had been removed by the addition of hydrazine as an oxygen scavenger, and the pH of feedwater was maintained between 9~10 with the addition of ammonia, leading to the formation of a magnetite layer. It was concluded that inappropriate feed water chemistry was the main cause of tubes failure, and the water chemistry regime must be changed by the Combined Water Treatment method. Thus, an oxidizing fluid was utilized and oxygen was maintained at a level of 150 to 300 ppb to stimulate the formation of a protective layer of hematite on top of the magnetite and prevent the occurrence of single-phase FAC. Simultaneously, the pH was adjusted in the range of 8.0 ~ 9.0 so that two phase-FAC could be avoided.

Our research efforts were focused on finding and developing quasicrystal-based (QC) alloys for structural applications. Numerous chemical compositions were tried out all of them being based on the Al-Mn system. A wide variety of methods and approaches was employed to synthesize, characterize, test and evaluate our alloys, especially LOM, SEM, EDS, EBSD, TEM, HRTEM, SAED, X-ray CT, DTA, DSC, XRD, Rietveld calculations, thermodynamic considerations, mechanical and nano-mechanical testing, and corrosion resistance assessment. More than twelve pure elements or their combinations were introduced into Al-Mn based alloys, but only some have proven to promote the formation of QCs, when sufficiently high cooling rates were employed. Furthermore, an introduction of modifiers into Al-Mn-based melts was also tested to assess their ability to ease the formation and growth of metastable QCs. We were able to show that QCs will grow in-situ during the solidification of the Al-Mn-based liquid alloy. This provided us with metal matrix-quasicrystal (MMQC) composite materials reaching Yield Strength (YS) up to 400 MPa, elongations in excess of 30 % and corrosion resistance comparable to that achievable in commercial 6XXX alloy series. Deformation behavior of macro-sized MMQC composites was also investigated, and the deformation mechanism in QC particles on the nano-scale was examined through in-situ nano-tensile and nano-compression experiments. QC particles as MMQC constituents have been shown to have the ability to undergo severe plastic deformation without forming cracks or cleavage. The introduction of various inoculants into the Al-Mn based melt proved to influence the formation of QCs during solidification of the melt by serving as a substrate for QCs to grow.

Metallic alloys show complex chemistry that is not yet understood so far. It has been widely accepted that behind the composition selection lies a short-range-order mechanism for solid solutions. The present paper addresses this fundamental question by examining the face-centered-cubic Cu-Zn a-brasses. A new structural approach, the cluster-plus-glue-atom model, is introduced, which suits specifically for the description of short-range-order structures in disordered systems. Two types of formulas are pointed out, [Zn-Cu12]Zn1,6 and [Zn-Cu12](Zn,Cu)6, which explain the a-brasses listed in the American Society for Testing and Materials (ASTM) specifications. In these formulas, the bracketed parts represent the 1st-neighbor cluster, and each cluster is matched with one to six 2nd-neighbor Zn atoms or with six mixed (Zn,Cu) atoms. Such a cluster-based formalism describes the 1st- and 2nd-neighbor local atomic units where the solute and solvent interactions are ideally satisfied. The Cu-Ni industrial alloys are also explained, thus proving the universality of the cluster-formula approach in understanding the alloy selections. The revelation of the composition formulas for the Cu-(Zn,Ni) industrial alloys points to the common existence of simple composition rules behind seemingly complex chemistry of industrial alloys, thus offering a fundamental and practical method towards composition interpretations of all kinds of alloys.

This talk presents my personal understanding of the contributions of prof. Jean-Marie Dubois and his commitment to achievements in science and technology. Prof. Jean-Marie Dubois was nominated Honorary Member of the Jo�ef Stefan Institute in Slovenia because of his long-term cooperation with the Institute. He is one of the six honorary member of the Institute in the 70 years of history. As the CEO of the Institute I am grateful for his contributions and I admire his engagement in the promotion and education of young researchers in Slovenia and elsewhere. His contribution in multiple European projects in which we participated, is invaluable.

One of the key issues in the further understanding of chemical ad physical behaviors of intermetallic compounds is complexity of their crystal structures. Structural complexity of intermetallic compounds may be described from the points of view of crystallographic features (number of atoms, symmetry), of chemical and crystallographic order/disorder, or of thermodynamic factors (phase diagrams, formation reactions), etc.. On base of crystallographic description, a special family of intermetallic compounds � the so-called complex metallic alloys or phases (CMA) � was defined. Neither electronic nor thermal transport behaviors follow strictly the crystallographic understanding of structural complexity in CMA. Nevertheless, recently was shown that the reduced lattice thermal conductivity of intermetallic type-I clathrates without vacancies and with respect to such with ordered vacancies suggests that disordered vacancies disturb the heat transport more efficiently as the electronic transport. Further insights are achieved considering the spatial separation of regions with different chemical bonding in the content of structural complexity.

One of the key issues in the further understanding of chemical ad physical behaviors of intermetallic compounds is complexity of their crystal structures. Structural complexity of intermetallic compounds may be described from the points of view of crystallographic features (number of atoms, symmetry), of chemical and crystallographic order/disorder, or of thermodynamic factors (phase diagrams, formation reactions), etc.. On base of crystallographic description, a special family of intermetallic compounds � the so-called complex metallic alloys or phases (CMA) � was defined. Neither electronic nor thermal transport behaviors follow strictly the crystallographic understanding of structural complexity in CMA. Nevertheless, recently was shown that the reduced lattice thermal conductivity of intermetallic type-I clathrates without vacancies and with respect to such with ordered vacancies suggests that disordered vacancies disturb the heat transport more efficiently as the electronic transport. Further insights are achieved considering the spatial separation of regions with different chemical bonding in the content of structural complexity.

In spite of the obvious fundamental as well as engineering interests in eutectic alloys, prominent especially for their low-melting points, the structure and composition of eutectic liquids remain open issues. We have developed a so-called cluster-plus-glue-atom model that suits specially for the description of short-range-order structures in quasicrystals, amorphous alloys, and solid solutions. In this model, any structure is dissociated into a 1st-neighbor coordination polyhedral cluster part and a glue atom part that are situated at the 2nd-neighbors and beyond, outside the cluster part. Then the structure can be expressed by a cluster formula in the form of [cluster]gluex, where the cluster is the coordination polyhedron representative of the 1st-neighbor of the structure, and the glue atoms are located in-between the clusters, marking the short-range order feature on and beyond the 2nd-neighbors. In the present work, this model is applied in establishing the local unit model for eutectic liquids, assuming that a eutectic structural unit consists of two stable subunits, each formulated from the relevant eutectic phases. Such a model is well validated in the B-containing eutectics (except those located by the extreme phase diagram ends), within accuracies below 1 at.%. The dual cluster formulas vary extensively and are rarely identical in different systems. Special cluster matching is pointed out, for instance CN12 cuboctahedron - CN9 capped trigonal prism, and CN12 rhombi-dodecahedron - CN10 octahedral antiprism are frequently combined.

Metallic alloys follow well-established composition rules but their complex chemistries are not yet understood so far, despite their long history and close ties with our daily life. The present talk addresses this fundamental question using a new structural approach, the cluster-plus-glue-atom model, which gives simple composition formulas for all kinds of metallic alloys including quasicrystals, metallic glasses, and solid-solution-based industrial alloys. This model dissociates any structure into a 1st-neighbor cluster plus a few outer-shell glue atoms, so that it can be expressed in terms of the cluster formulas as [cluster](glue atoms). I will first present the pathway that leads to the proposition of this new theory, which dates back to the good old days working with Prof. Jean-Marie Dubois at the Ecole des Mines de Nancy in the late 80��s and early 90��s. Then I will discuss the basics about the model and the physics behind. Finally, I will use the model to analyze alloy examples covering Al-based quasicrystals, bulk metallic glasses, and solid solution alloys. I will point out their common structural origins within the framework of our model. The revelation of the composition formulas points to the common existence of simple composition rules behind seemingly complex chemistries of different kinds of alloys, thus offering a practical and fundamental method towards their composition interpretations and eventually designing.

With semiconductor properties similar to crystalline phase beta-FeSi2 and higher absorption coefficients, the semiconducting amorphous Fe-Si films are potential materials for large-area electronics. In this paper, magnetron sputtering method was used to prepare FexSi100-x (x=0~69.7at. %) amorphous films on Si (100) and Al2O3 (0001) substrates. The analyses of the optical band gap, resistivity, initial crystallization temperature and crystalline phase showed regional variations of properties in the film. Furthermore, [cluster](glue atom)1or3 amorphous structural model was used to study the local structures of the films. It was found that there were three short-range ordered cluster structures including [Si-Si4], [Fe-Si7Fe6] and [Fe-Si8Fe2], which were respectively determined by Si, ��-FeSi and beta-FeSi2 phases in the entire composition range. These three local structures, alone or superimposed, were divided into three main regions. The results confirmed that the characteristic short-range order of crystalline phase ultimately determined the semiconductor properties of amorphous Fe-Si films, and verified the validity of amorphous structural model based on clusters for analyzing amorphous FexSi100-x. These studies are of practical significance to expand the applications of amorphous FexSi100-x films with semiconductor properties.

The area of dental ceramic materials was revolutionized with the introduction of aesthetically more appealing, metal-free ceramic materials that can withstand chewing forces and are nowadays designed and fabricated not only in a way that marginal leakage is no longer a problem, but also with increased biocompatibility. It is generally agreed that the modern area of dental care started 15 to 20 years ago with the introduction of novel dental composite materials and zirconia ceramics for conservative and prosthetic dentistry. Furthermore, bioactive ceramic materials are now attracting interest, especially in oral surgery and endodontics. Calcium and/or aluminum silicates, bioglass and hydroxyapatite are the materials of choice.
In the present paper, the state of the art for dental ceramics used in modern clinical practice will be presented, followed by a discussion on future, potential, advanced solutions for problems related to dental ceramic materials. For example, given its high elastic modulus, some of our research work was focused on the use of advanced materials engineering to fabricate high-performance, moderately porous, zirconia dental ceramics with a lowered elastic modulus and, therefore, an increased compatibility with dentine. The zirconia`s high chemical inertness, resulting in insufficient bonding abilities, was solved by using a non-invasive, surface-functionalization technique for the application of an adhesive coating to the zirconia surface, which significantly improves the adhesive abilities, opening several options for minimally invasive dental procedures. Most recently, we have addressed the rheological and bioactive properties of commercially available MTA materials in such a way that their use could be expanded beyond dental practices specialized in endodontics.

Based on the idea of "setting up a nanolab inside a TEM", we present our recent progress in nanomaterials research including in situ growth, nanofabrication with atomic resolution, in situ property characterization, nanodevice construction and possible applications. The electron beam can be used as a tool to induce nanofabrication on the atomic scale. Additional probes from a special-designed holder provide the possibility to further manipulate and measure the electric/mechanical properties of the nanostructures in the small specimen chamber of a TEM. Recently, the optical signal also was introduced into the electron microscope to enrich the coverage of investigation inside the multifunctional nanolab. All phenomena from the in-situ experiments can be recorded in real time with atomic resolution.

Based on the idea of "setting up a nanolab inside a TEM", we present our recent progress in nanomaterials research including in situ growth, nanofabrication with atomic resolution, in situ property characterization, nanodevice construction and possible applications. The electron beam can be used as a tool to induce nanofabrication on the atomic scale. Additional probes from a special-designed holder provide the possibility to further manipulate and measure the electric/mechanical properties of the nanostructures in the small specimen chamber of a TEM. Recently, the optical signal also was introduced into the electron microscope to enrich the coverage of investigation inside the multifunctional nanolab. All phenomena from the in-situ experiments can be recorded in real time with atomic resolution.

A cluster formula [Ni-Fe12](Cr2Ni) was used to formulate the compositions of maraging stainless steels and a new steel was developed on the basis of Co-free Custom 465, with much reduced Ti contents. These alloys were prepared by the copper mould suction casting method, then solid-solution treated at 1273 K for 1 h followed by water-quenching, and finally aged at 783 K for 3 h. The experimental results showed that the multi-element alloying results in Ni3M precipitation on the martensite, which enhances the strengths of alloys sharply after ageing treatment. Among them, the aged Fe74.91Ni8.82Cr11.62Mo1.34Ti0.67Nb0.32Al0.19V0.36Cu1.78 wt% has higher tensile strengths with YS=1456 MPa and UTS=1494 MPa. It also exhibits good corrosion-resistance in 3.5 wt% NaCl solution.

Cardio-vascular diseases such as heart attack are one of the major causes of mortality worldwide. The mechanical properties of blood vessels play an important role in this area. Tissue therapy seems to be a promising way for such diseases. The engineered tissue must be as close as possible to the real material. Then modelling the mechanical behavior of the latter is of paramount importance. Due to its complexity, we believe that a top-down phenomenological approach is appropriate. Adopting a constrained microstretch approach (dilatation elasticity), we show that the approach is meaningful in the case of cardiac tissue with respect to heart infarct.

To be able to observe atoms in solids has been an old dream in materials science.
Unfortunately, all attempts undertaken between the invention of the electron microscope in the 1930s and the end of the 1980s, to find a way to correct lens aberrations in electron optics and to venture into atomic dimensions failed entirely. The reason for this lies in a fundamental law of physics: Gauss Law of Magnetism, one of Maxwell's equations, prohibiting the construction of diverging lenses which according to Abbe's principles of optics are indispensable for lens aberration correction. Between 1991 and 1997 Haider et al. [1] could show that this obstacle can be overcome employing magnetic multipole lenses, and on this basis they succeeded to construct the world's first aberration-corrected transmission electron
microscope.
The new generation of commercial electron microscopes based on this invention brought about a change in paradigm in materials science. Atomic resolution investigations, by both conventional transmission (TEM) and by scanning transmission (STEM) electron microscopy are today part of most innovative materials studies [2]. This includes not only structural investigations but also atomically resolved local elemental analysis by quantitative contrast analysis and by atomically resolved electron-energy loss spectroscopy (EELS).
The lecture will start with a concise historical overview and an introduction into the principles of aberration correction in modern electron optics. In the second half typical examples of atomic-resolution electron microscopy of materials will be presented. The emphasis will be on recent results on functional oxides, in particular dielectric materials. These demonstrate the enabling role of modern electron microscopy for materials science studies. In fact it is intriguing that today, by combination of modern electron optics with computer-based image analysis, atomic positions can be measured at the precision of 1 picometer, i.e. one hundredth of the diameter of a hydrogen atom [3].
[1] M. Haider, S. Uhlemann, H. Rose, B. Kabius & K. Urban, Nature 392, 768 (1998).
[2] K. Urban, Science 321, 506 (2008).
[3] C.L. Jia, S.B. Mi, J. Barthel, D.W. Wang, R.E. Dunin-Borkowski, K.W. Urban &
A. Thust, Nature Materials 13, 1044 (2014)

Fe-based bulk metallic glasses (BMGs) have been attracted great attention since the first synthesis in 1995 due to their unique magnetic and mechanical properties. In this talk, FeNiPC alloys with high strength and unprecedented compressive plasticity at room temperature, which have not been obtained in conventional Fe-based crystalline alloys, will be reported. The mechanism of ductile-to-brittle transition for Fe-based BMGs was also investigated. It was discovered that the ductile Fe-based BMG is composed of unique clusters mainly linked by less directional metal-metal bonds which are inclined to accommodate shear strain and absorbed energy in the front of the crack tip. This conclusion was further verified by the X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy experiments of brittle to ductile Fe-based glassy systems. The results also indicate a strong correlation between the p-d hybridization and plasticity, verifying that the transition from brittle to ductile is due to the change of bonding characteristics in atomic configurations.

The main experimental difficulty in extracting the crystal structure and chemical information from individual nanostructures and interfaces is often associated with a generally weak underlying signal. Spatially resolved Analytical Electron Microscopy (AEM), which typically combines Scanning Transmission Electron Microscopy (STEM) with different spectroscopy techniques, such as Energy Dispersive X-ray Spectroscopy (EDXS) and Electron Energy-Loss Spectroscopy (EELS) has been revolutionised the characterization and understanding of nanostructures and internal interfaces in materials by providing atomic-scale structural and chemical information. Nowadays, modern probe aberration-corrected STEMs with the electron probe size below 1 � allow combined atomic resolution imaging and spectroscopy of nanostructures and associated structural defects. In this presentation, the above described analytical capabilities will be discussed through the perspective of high-resolution AEM studies performed on three different metallic systems. These are complex metallic nanostructures with hollow interiors, heavy rare earth (HRE)-rich Nd�Fe�B-based magnets and (Ca,Gd)Cu5 single crystal.
Complex metallic nanostructures with hollow interiors: by the combined information of STEM imaging and EELS we were able to measure the nitrogen gas pressure within individual nanospheres, which provide us with vital clues on how gas-filled hollow spheres could be fabricated in various complex metallic systems via a single-step procedure by the ablation of a metallic or alloy-based target into ambient nitrogen gas.
HRE-rich Nd�Fe�B-based magnets: Small amounts of the HREs (Dy, Tb) that partially replace the Nd in the grain-boundary diffusion process have a large, positive influence on the coercivity of the whole Nd�Fe�B-based magnet. Their reliable quantification is essential for optimising hard-magnet processing, but often compromised not only because of the limitations due to the analytical detection limits, but also because of the strong signal overlap that is found in EDXS and EELS. In this study, we report on the possible pitfalls of the related measurement techniques. The study yielded a step-by-step procedure for correctly assessing the true concentration of the HREs in a TEM by applying quantitative EELS analysis of grain boundaries and triple pockets.
(Ca,Gd)Cu5 single crystal: This model complex alloy was selected to demonstrate the strength of two complementary atomic resolution imaging modes; High-Angle Annular Dark-Field (HAADF) and Annular Bright-Field (ABF) STEM combined with STEM image simulations based on a given structural model and experimental microscope electron-optical parameters. When these techniques are used in a combined manner they can provide comprehensive information about the underlying crystal structure in terms of atoms positions and atom types at the atomic scale.

Quasicrystals (QC�s) exhibit particular features when compared to a conventional crystalline solid materials. They present an aperiodic, however, highly ordered atomic structure. These phases exhibit a variety of interesting properties for application as protective coatings, including high hardness, low friction coefficient, high corrosion resistance in acid medium, high resistance to oxidation and low thermal conductivity. In the present work, several aluminum based alloys in the systems Al-Fe-Cu, Al-Cu-Fe-Cr, Al-Cu-Fe-Ni, Al-Ni-Co, Al-Ni-Co-Cr, Al-Ni-Co-Cu and Al-Co-Fe-Cr have been assessed, with the objective to develop new quasicrystalline compositions with improved corrosion, thermal and tribological properties.
Rapid solidification methods, such as melt-spinning, atomization, HVOF and arc melting, were used. The microstructures were characterized by transmission and scanning electron microscopy (TEM and SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Evaluation of the properties included mechanical and pin-on-plate wear tests and Vickers Microhardness. Al-Cu-Fe and Al-Co-Ni are systems well known for the formation of quasicrystalline phases and the present work aimed to modify ternary quasicrystalline compositions of those alloys by adding corrosion resistant elements, such as Cr, Ni and Cu. The Al-Co-Fe-Cr system was studied due to their known good thermal insulation properties.
Quasicrystalline phases were observed in most alloys of the Al-Cu-Fe-(Cr,Ni) and Al-Ni-Co-(Cr,Cu) systems. The Al-Co-Fe-Cr system did not present the formation of quasicrystalline phases; instead, we observed the formation of two intermetallic phases, which are quaternary extensions of Al5Co2 and Al13Co4 phases. The coatings fabricated from this alloy presented extremely low friction coefficient values and Vickers microhardness around 500 HV in the coating material and up to 1000 HV in the bulk material. The results from this assessment of potential quaternary quasicrystalline alloys indicated a promising way of tailoring new quasicrystalline compositions with improved properties such as corrosion behavior, thermal insulation and low friction coefficient, which are desirable properties for coating applications.

Dental implants are well known medical devices. Placing implants seem also well controlled. The latter is true as long as the bone of the jaw is large enough and has the right microstructure. The consideration of atypical cases requires the engineering of new implants and the analysis of their mechanical interaction with bone tissue. The constitutive modelling of the latter is imperative. Due to its complexity, we believe that a top-down phenomenological approach is appropriate. In this work, bone tissue is considered as a micropolar medium. Using a specific developed numerical tool, the work analyses the response of such material to external stimuli.

The development of new materials, with the goal to meet the needs of near-future technological challenges in energy or environment issues particularly, is strongly dependent on the elaboration of ceramics with suitable morphologies, shapes and enhanced properties. This ambitious goal can be achieved by both utilizations of non-conventional chemical methods and the related preparation of tailored precursors.
In the case of non-oxide ceramics, the pyrolysis of the preceramic precursor, either molecular or polymeric, is a useful process for preparing various inorganic materials with a controlled chemical composition and in complex shapes when suitable shaping processes are used. The general strategy to produce such materials can be described as a molecule-to-ceramic conversion, involving a complex sequence of physical and chemical modifications. This process can be divided into two sub-processes both starting from a single-source molecular precursor. The first route lies on the creation of polymeric intermediates, allowing a subsequent shaping step whereas the second method is related to a one-step access to specific shapes.
In this contribution, several examples of shaped-Polymer Derived nano-Ceramics will illustrate this elegant method as well as their use in energy applications, particularly for Hydrogen storage. We will focus on boron- and silicon-based PDCs displaying various forms and sizes, including monolith-type foams with hierarchical porosity, nanostructures including nanopowders and nanopolyhedrons, nanocomposites, nanowires. Micro-, meso-materials and other types of materials will be also described. On another hand, the elaboration of graphene-like BN nanocomposites will be also presented in the perspective of fabricating gas barriers as well as preliminary results of the ALD preparation of nitrides for energy applications.

The assessment of the mechanical properties of heart tissue which is very soft as other biological tissues should be done in a liquid environment. This is a necessary condition in order to avoid the degradation of the material properties due to drying. We believe that an appropriate experimental approach is the depth sensing indentation in liquid environment. The test, though being well mastered for conventional materials in ambient air, requires a deep investigation when it is performed in liquid environment. The work presented here is concerned with the way to extract the mechanical properties of a sample from the indention curve (load versus penetration curve) obtained in liquid environment.

In terms of the cluster-plus-glue-atom model, a good glass former conforms to a general composition formula [cluster](glue atoms)1 or 3, where the cluster is derived from a devitrification phase. However, an alloy phase usually contains multiple clusters and the selection rule of the so-called principal cluster should be specified. In this paper, two important properties of the principal clusters are emphasized, i.e., spherical periodicity and large cluster separation distance, both being structural features of metallic glasses. According to these two criteria, the principal clusters are rigorously identified in devitrification phases and are used to construct cluster formulas to explain Cu-(Zr,Hf), Ni-(Nb,Ta), Al-Ca, and Pd-Si bulk binary metallic glasses, as well as their relevant eutectic points.

We draw attention to A-B-C ternary alloys, in which the elemental constituents A, B and C are chosen in such a way that B-C interactions are repulsive, but A-B and A-C are attractive in the respective binary systems. Such �push-pull alloys� are reminiscent of amplifiers designed to amplify electric signals. Push-pull alloys amplify complexity, forming complex intermetallics with tens to thousands of atoms per unit cell. Few of them lead to the ultimate degree of complexity when quasiperiodic order substitutes for crystal periodicity, which opens the way to discovering unprecedented properties such as heat insulation in Al62Cu25Fe13 (at. %). Many more compounds are known today, which share the same elemental characteristics (the picture may be extended to specific binary alloys). The case of push-pull alloys will be exemplified with data obtained on several ternary systems such as Gd-Ca-Cu and Al-Sc-Cr alloys as well as magnetic materials based on (Gd,Al)-Cu-Fe metallic glasses.

Rare earth metals exhibit large, strain-dependent anisotropy associated with their strong spin-orbit coupling. There are both single-ion and two-ion contributions to the resulting magnetostriction. The linear, volume-conserving (Joulian) magnetostriction λ is an important functional property of ferromagnets that saturates with the magnetization, and depends on the directions of applied field and measured strain. However, the magnetocrystalline anisotropy also tends to impede the saturation of the magnetization and limit the usefulness of effect. This problem was elegantly overcome in the cubic Laves-phase ferromagnets RFe2 by using a mixture of rare-earths (Tb and Dy) with opposite signs of cubic anisotropy, but the same sign of linear magnetostriction. The (Dy,Tb)Fe2 alloys (�Terfenol-D�) hold the record for room-temperature saturation magnetization, λs ≈ 2000 ppm.
More recently, a different magnetostriction mechanism has been identified in Fe-Ga alloys (Gafenol), which exhibit a magnetostriction of up to 300 ppm due to tetragonal nanoinclusions that exist throughout the cubic A2 matrix. The magnetostriction is then related to the field-induced tetragonality of the matrix. Remarkably, this effect can be enhanced by up to a factor of five by incorporating tiny traces (~ 0.1%) of barely soluble rare-earth atoms into the Fe-Ga alloys. Values of magnetostriction approach those of Terfenol-D, with one hundred times less rare earth. Systematic investigations [1] reveal that the enhancement depends partly on the volume of the rare earth (regardless of whether it is magnetic or not), and partly on its quadrupole moment. Prospects for producing melt-textured or single crystal alloys to rival Terfenol-D will be discussed, as will recent claims [2] that Fe-Ga alloys exhibit �Non-Joulian� magnetostriction.
[1] He Yangkun et al, Giant heterogeneous magnetostriction in Fe-Ga alloys: effect of trace element doping, Acta Materialia (in press) 2016
[2] H. D. Chopra and M. Wuttig, Non-Joulian magnetostriction, Nature 521 340 (2015)

The task of probing magnetic structures on a local scale, as opposed to bulk measurements which average over larger volumes, is one that lends itself well to the use of Magnetic Force Microscopy (MFM). A member of the scanning probe microscopy family. In this technique, a sharp magnetically sensitive tip mounted on a compliant cantilever beam is brought into close proximity to a magnetic sample. Varying interactions between the magnetic field of the sample and the stray field of the tip lead to changes in the status of the cantilever. As such magnetic force microscope with the lateral resolution less than 100 nm, and the ability to resolve both magnetic and topographic features of the sample, in order to better elucidate the interplay between the two. For the in-field MFM measurements on electroplated Fe-Pd and Co-Pt NWs a home-made stage was used. The maximum external field applied to the NWs was applied via permanent magnet with the maximum applied etrean field (Hmax~240 kA/m) which�s direction was varied. Using electrodeposition into anodic aluminium oxide membranes fcc Fe48Pd52 and hcp Co65Pt35 NWs with diameters of ≈ 200 nm and lengths of ≈ 3.5 �m were synthesised. Magnetic force microscopy on a single Fe-Pd NW revealed single-domain behaviour with the easy axis of magnetization along the long axis of the NW. The magnetization-switching behaviour of a single Fe-Pd NW studied with MFM suggested a square-shaped magnetization curve (M/Ms=1) with HC ≈ 3.2 kA/m. By using in-field MFM technique, the effect of dipolar interactions in Fe-Pd array of NWs still embedded in the AAO was examined and found that the dipolar interactions greatly reduce the remanence and the switching-field distribution of the Fe-Pd NW array. In the case of the Co-Pt NWs the texturing of the direction [100] was observed that suggests the uniaxial anisotropy perpendicular to NW long axis. The subsequent magnetic results obtained via �bulk� methods VSM and first order reversal curves (FORC), allowed us to conclude that Co-Pt NWs with hcp crystal structure had a uniaxial anisotropy perpendicular to NW long axis. This was found to further to result in a unique periodic domain structure observed with MFM. By using an adopted equation to calculate the period of the stripes or the domain width for the nanowires we estimated a domain width of Wcal ≈250 nm to minimize the total energy, which is in excellent agreement with the present observations. Finite-element calculations have also shown that the transverse magnetization configuration in such a type of domain pattern is the state with the lowest energy that can be applicable in the newest version of race track memory devices with perpendicular anisotropy.

Even the slightest content of species segregating at the grain boundaries (GBs) of a polycrystalline material can dramatically change its physical (mechanical, thermal, electrical, optical) features and its lifetime. While some nonmetallic species may improve its mechanical properties, sulfur segregating in nickel GBs yields its embrittlement, when the S-content reaches a critical concentration specific of a ductile-brittle transition [1]. Recent observations of different GBs using the NanoSIMS device revealed that one has to account for the atomic-scale structure of the GB to understand its S content, as different GBs with different orientations display different enrichments [2]. But the expected small thickness of the segregated layers prevent a straightforward observation and requires complementary atomic-scale models.<br />Literature abounds with first-principles computations on the Ni-S, but only very few and specific GBs can be handled for tractability reasons. While many very efficient interatomic potentials can deal with pure metals and metallic alloys, up-to-date only the ReaxFF approach allows to account for Ni-S at the atomic scale [3]. We discuss its use to reach an atomic-scale description of a given GB (chemistry-structure coupling) and the challenges to solve both from computational and experimental developments to describe the interface of Ni-S GBs.<br />[1] J. K. Heuer, P. R. Okamoto, N. Q. Lam and J. F. Stubbins, Applied Physics Letters 76 (23), 3403-3405 (2000)<br />[2] F. Christien, C. Downing, K.L. Moore, C.R.M. Grovenor, Surface and Interface Analysis 44, 377-387 (2012)<br />[3] H.-P. Chen, R. K. Kalia, E. Kaxiras, G. Lu, A. Nakano, K. Nomura, A. C. T. van Duin, P. Vashishta, and Z. Yuan, Phys. Rev. Lett. 104, 155502 (2010)

Steel plates have been coated by Al-based quasicrystal obtained by atomization from the liquid state and sprayed using a high-velocity oxygen-fuel flame torch. Static and sliding contact experiments were carried out in order to assess on the one hand the mechanical properties of the quasicrystal and on the other hand the friction and related properties such as wear and resistance to scratch. Besides these conventional properties, indentation experiments reveal the porous nature of the thick coating. Scratch test experiments pinpoint the low elastic recovery of the sample (despite a low plastic deformation at high loads). Pin on disc experiments reveals the abrasive nature of the coating.<br />In the end, the friction properties of this type of coating appear excellent in comparison to many state-of-the-art surface layers. The talk will summarize such findings and will compare them to solutions most frequently used in mechanical devices.

The KNb3O8 triniobate potassium (Amam (63), a = 8.903 �, b = 21.160 �, c = 3.799 �) and the K4Nb6O17 (P21nb (33); a = 7.83 �, b = 33.2 �, c = 6.46 �) phases are both layered compounds that show excellent photocatalytic activity for degradation of organic contaminants in water, CO2 and hazardous microorganisms and intercalation properties together with electrochemical performances that are attractive as anode active materials for sodium-ion battery. In this study, we report the first synthesis of KNb3O8 niobate in thin film form, and the first growth of the phase K4Nb6O17 with epitaxial relationships with the substrate. The films were prepared by pulsed laser deposition on (100)SrTiO3 (STO) and characterized by X-ray diffraction, scanning and transmission electron microscopy, and X-ray energy dispersive spectroscopy. The KNb3O8 films, made of elongated crystals (500 nm long and 50-75 nm wide), with the [100] direction parallel to the elongation direction, are well-crystallized. They are (010)-preferentially oriented and present epitaxial relationships with the substrate, namely (010)KNb3O8 // (100)STO, [100] KNb3O8 // [010]STO and [001]KNb3O8 // [001]STO. The KNb2.66O7.73 composition with a very narrow range is measured, slight potassium amount changes leading to the growth of other niobates (as K3Nb6O19 and K4Nb6O17). The K4Nb6O17 films grow as rectangular lamellas of several microns with the following relationships with the substrate: (010) K4Nb6O17 // (100) STO, [100] K4Nb6O17 // [010] STO, [001] K4Nb6O17 // [001] STO. In both compound films, Sn was intercalated in order to reduce the bandgap of the niobates.

In modern society, metallic materials are crucially important (e.g. for applications related to energy, safety, infrastructure, transportation, health, medicine, life sciences, IT). Contemporary examples of inherent challenges to be overcome are the design of ultrahigh specific strength materials. There is a critical need for successful developments in this area in particular for reduced energy consumption, reduction of pollutant emissions and passenger safety. Also, the ageing society makes biomedical materials for implant and stent design crucially important. A drawback of nearly all current high strength metallic materials is that they lack ductility (i.e. are brittle and hard to form) - or on the opposite side, they may be highly ductile but lack strength. Hence, it is mandatory to develop new routes for a creation of tailored metallic materials based on hierarchical hybrid structures enabling property as well as function optimization. One starting point along these lines is the design of monolithic amorphous materials or bulk micro-, ultrafine- or nano-structured composite structures with intrinsic length-scale modulation and phase transformation under highly non-equilibrium conditions. This can include the incorporation of dispersed phases which are close to or beyond their thermodynamic and mechanical stability limit thus forming hierarchically structured hybrid and ductile/tough alloys. Alternatively, the material itself can be designed in a manner such that it is on the verge of its thermodynamic/mechanical stability.
This talk will present recent results obtained for metallic glass-based hybrid structures with transformation effects at different length-scales and microcrystalline-grained hybrid structures based on elastic instabilities and modulated length-scale. The deformation behaviour and possible phase transitions during deformation will be related to the intrinsic properties of the phases as well as the microstructure of the material including heterogeneities and length-scale modulation in order to derive guidelines for the design of macroscopically ductile high-strength materials. Finally, the results will be critically assessed from the viewpoint of possible scaling-up for technological applications and the use of simple and cost effective processing technologies.

Nanostructured Nd�Fe�B-type materials produced by melt-spinning (MS) are used in a variety of applications in the electronics, automotive, and sensor industries. The very rapid MS process leads to flake-like powders with metastable, nanoscale, Nd2Fe14B grains. These powders are then formed into net shaped, isotropic, polymer-bonded magnets, or they are hot formed into fully dense, metallic magnets that are isotropic and anisotropic. These fully dense magnets are usually produced with a conventional hot press without the inclusion of additives before the hot pressing. As a result, their properties, particularly the coercivity (Hci), are insufficient at automotive-relevant temperatures of 100�150 �C since the material Hci has a large temperature coefficient. In this study, we instead add a thin layer of TbF3 to the melt-spun ribbons before their hot consolidation to enhance the coercivity through a diffusion-based, partial substitution of the Nd by Tb. This effect is accomplished by applying extremely rapid, spark- plasma sintering to minimize any growth of the nanoscale Nd2Fe14B grains during consolidation. By using field-emission gun scanning electron microscope (FEG-SEM) with the energy dispersive spectroscopy (EDS), and high-resolution transmission electron microscope (HRTEM) we confirmed the formation of the core-shell-type microstructure, which results in increased coercivity.
The result is a magnet with very high-coercivity with drastically reduced amounts of heavy rare earth that is suitable for high-temperature applications. This work clearly demonstrates how rapidly formed, metastable states can provide us with properties that are unobtainable with conventional techniques.

The unusual tendency of aluminium to form quasicrystalline alloys is not the only anomalous property of this metal atom. It has another, i.e., when covalently bonded to nitrogen (aluminium nitride; AlN), its propensity to decompose in humid environments, i.e., the tendency to undergo hydrolysis, which can lead to a complete degradation of the material, is unique in metal nitrides. Although this form of hydrolysis has been known for a long time � about a century ago it was exploited for the production of ammonia � it is generally considered as a nuisance, because it prevents the aqueous powder-processing of AlN-based ceramics. However, we have shown that this hydrolysis can also be exploited.
The present paper will present our recent, in-depth studies of the solid reaction products of the hydrolysis along with its reaction kinetics, which has opened up numerous possibilities for the exploitation of this naturally driven process in the area of advanced materials engineering. On one hand, we can use it in the hydrolysis-assisted solidification (HAS) of ceramic suspensions for the processing of high-performance, porous ceramics. On the other, we can exploit it for the synthesis of hierarchically self-assembled, mesostructured, hydrous aluminium oxide powders and/or coatings. For example, we showed that the coatings are suitable as templates for self-cleaning, super-hydrophobic surfaces or in dentistry as adhesive coatings for cementing, the recently very popular, yttria-stabilized tetragonal zirconia. On the other hand, the hierarchically self-assembled, mesostructured powder can be used either as a precursor for the processing of porous transient alumina monoliths with hierarchical heterogeneities or for the fabrication of the photocatalytically active &#947;-Al2O3/TiO2 hetero-structures with a superior quantum efficiency.

Metallic glasses exhibit unique properties due to their unusual amorphous microstructure. Because they do not possess slip systems and lattice dislocations as in crystalline materials, metallic glasses manifest large elastic deformation before yielding and show high yield stresses [1]. Bulk glassy/nanostructured Ti-based multicomponent alloys are attractive advanced high-strength materials for structural and functional applications, e.g. aerospace and biomedical industries [2]. Typically, the specific strength, elastic strain limits and corrosion resistance of such alloys are significantly higher than for conventional microcrystalline materials. However, the glass-forming ability (GFA) of titanium alloys is poor compared with other easy glass-forming alloys (e.g. Zr-, Cu-, Pd-, Fe-based alloys).
In this work we report on the structural competition and glass formation in two Ti-based systems with different GFA: Ti-Cu-Ni-Sn-Si-B and Ti-Zr-Si. The microstructures in the Ti50Cu20Ni24Sn3Si2B1 glass-forming alloy were tailored by melt-spinning and copper mold casting into different sizes. A glassy phase dominates in the as-spun ribbon, while the as-cast �2 and �3 mm rods are metallic glass matrix composites composed of micrometer-sized bcc NiTi dendrites surrounded by a thin metallic glass network as well as a fine distribution of CuTi3 intermetallics. The glass-forming ability, thermal stability and microstructural characteristics of as-cast rods and melt-spun ribbons were investigated by differential scanning calorimetry (DSC), X-ray diffraction and transmission electron microscopy. Crystallization behavior of Ti-Cu-Ni-Sn-Si-B and Ti-Zr-Si glassy ribbons was investigated by viscosity measurements and DSC in the mode of isochronal and isothermal annealing. The viscosity was measured by parallel plate rheometry in a large time and temperature range and compared with the DSC measurements near the glass transition temperature.
Support by the EC (FP7 VitriMetTech-ITN) is gratefully acknowledged.
[1] A.L. Greer, Materials Today 12 (2009) 14
[3] M. Calin, A. Gebert, A.C. Ghinea, P.F. Gostin, S. Abdi, C. Mickel, J. Eckert, Mat.Sci.Eng. C 33 (2013) 875-883

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