Editors: | F. Kongoli, F. Marquis, N. Chikhradze, T. Prikhna |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2019 |
Pages: | 174 pages |
ISBN: | 978-1-989820-10-0 |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
Significant enhancement of properties may be achieved through hybrid materials produced by newly emerging techniques of shear mixing [1]. It was shown that properties obtained by severe plastic co-deformation of dissimilar metallic materials are far outside of the expected properties of composite materials due to several physical phenomena observed, such as extension of solid solubility in immiscible metals, formation of non-equilibrium phases and reduction of grain size to a range of 10-20 nm near the interface. This level of nanostructuring that is accessible in hybrid materials is shown to be unreachable in single constituent materials.
The idea of manufacturing material hybrids with simultaneous nanostructuring by SPD to reach new levels of properties is quite appealing. The architecture of hybrid materials is based not only on the design of the constituents and their volume fraction, but also on optimisation of the width and composition of the interface zone. Moreover, the understanding of physical mechanisms involved in interface formation and triggered by severe shear deformation under hydrostatic pressure is crucial for the architecture of hybrid materials with enhanced properties.
One of the important factors for lightweight application examples is focused on shear-assisted interface formation in composite sheets of Interstitial-Free steel with Al or Cu interlayers [2, 3].
Al-IF steel and Cu-IF steel, multilayered composite sheets with different volume fractions of aluminium or copper, were produced by accumulative roll bonding (ARB) and Asymmetric Accumulative Roll Bonding (AARB), the latter introducing additional shear strain. The IF steel and Al/Cu alloy sheets were stacked in a sandwich-like structure and roll-bonded by two passes with varying roll diameter ratios (dr) equal to 1 and 2 for ARB and AARB processes, respectively. This work shows the effect of shear strain on the formation of the interface zone. The interface zone thickness, formed by intermixing and diffusion, was characterised by several different techniques, such as STEM EDX line scan, HRTEM and Atom Probe. Furthermore, finite element simulations of both processes were conducted to determine the level of interfacial shear strain.
Conclusions:
- Severe Plastic Deformation (SPD) processes were shown to be a useful tool to produce hybrid materials with concurrent nano-structuring of the constituents.
- Shear strain, hydrostatic pressure and temperature of SPD processing play an important role in enhancement of the formation and properties of measurable interfaces.
- The width of the interfacial zone correlates directly with the magnitude of the shear strain and architecture of the hybrid material.
- The volume fraction and the nature of the interfaces play a decisive role in the improvement of mechanical and physical properties of a hybrid material.