SIPS 2018

DETAILLED PROGRAM OVERVIEW

Maxwell-Boltzmann Energetics-enabled Design of Ball Milled Reactive Fractal Materials
Haris Doumanidis¹;
¹NAZARBAYEV UNIVERSITY, Astana, Kazakhstan;
PAPER: 53/Manufacturing/Regular (Oral)
SCHEDULED: 17:10/Wed./Mar Azul (50/1st)

ABSTRACT:
Ignitable reactive bimetallic nanostructured systems, such as Al-Ni multilayers, have been of recent importance for rapid thermal annealing and joining in microelectronics, self-heating materials, and biomedical analysis and drug delivery. Design of their self-propagating exothermic reaction (SPER) properties, such as ignition threshold, front velocity, enthalpic release and adiabatic temperature profile, through design of their fractal (Apollonian pack or Brownian network) structure calls for understanding of their fabrication processing conditions, such as surface impact and bulk deformation in ball milling (BM) of metal powders. However, theoretical and computational analysis of BM in the literature only addresses the kinematics of milling balls by computationally expensive discrete element methods (DEM) and empirical correlations. Recently, a numerical model of the structure-property connection in bimetallic layer SPER capturing the kinetics and dynamics of conduction, diffusion and reaction, as well as a predictive real-time simulation of the process-structure relation in BM multilayers based on Hertzian contact, Coulomb friction and Castiglianoa's deformation theorem of Lagrangian domain primitives has been introduced by the authors' team, offering valuable insights for design. This work elaborates on the theoretical underpinnings of the energetics in BM processing of multi-metallic powders into reactive multilayer material structures, based on statistical mechanics akin to the Brownian kinetics of ideal gases and solutions. Understanding of analogies and differences between kinetic theory and BM fabrication in thermomechanical equilibrium with the container, gravitational field and surface effects from atmosphere and process control agents, and impact coupling in milling ball and particulate interactions is specifically pursued. The theory leads to a Maxwell-Boltzmann probability density function for the collision velocity and energy spectra, along with a uniform distribution of BM impact directionality. This mono-parametric descriptive formulation is calibrated and validated by DEM and experimental data from the bibliography and laboratory tests, and is integrated with the full predictive model of process-structure mechanics above. Simulations of the stochastic multi-layer lamellar structure of bimetallic powders during the BM process are validated against scanning electron microscopy (SEM) sections of Al-Ni particulates in experimental low-energy ball milling, matching the fractal Hausdorff dimensions of the micrographs. This theory-based comprehensive computational tool of the full process-structure-property connection provides new understanding of the reactive materials and enables off-line design approaches for their structure along with real-time process control of BM.

References:
[1] Rebholz, C., Gunduz, I.E., Ando T. and Doumanidis, C.C., "Miniature Thermal Matches: From Nanoheaters to Reactive Fractals", Materials Research Express 2 (2015) 045009 (8 pages)
[2] Doumanidis, C.C., Gunduz, I.E., Rebholz, C. and Doumanidis, C.C., "Real-time Computational Model of Ball-Milled Fractal Structures", ASME J. of Nanotechnology in Eng. & Med. (2015) doi:10.1115/1.4031276 (http://nanoengineeringmedical.asmedigitalcollection.asme.org/article.aspx?articleid=2428190)
[3] Doumanidis, C.C; Al Kaabi, H.A; Alzaabi, A.S.M; Gunduz, I.E; Rebholz, C; Doumanidis, C.C; "Brownian
Kinetics of Ball Milling for Particulate Structural Modeling", Advanced Powder Techn. (submitted 2015)