MECHANISTIC PROCESSES INFLUENCING SHOCK CHEMISTRY IN POWDER MIXTURES OF THE TI-SI, TI-AL, AND TI-B SYSTEMS

Shock-recovery experiments were performed on Ti-Si, Ti-Al, and Ti-B po wder mixtures to produce compacts of reacted and unreacted states to c haracterize the reaction product microstructure as well as the shock-c ompressed configuration of unreacted constituents. Microstructural and X-ray diffraction (XRD) peak broadening analyses were performed on un reacted compacts to determine the configurational changes occurring du ring shock compression of powders and to quantify the differences in t he deformation response of the reactants in each system. The results o f the present work demonstrate that the mechanistic processes leading to shock-induced reactions are dominated by differences in the shock-c ompression response of the powder mixture reactants. It was establishe d that the propensity for initiation of shock-induced chemical reactio n decreases from Ti-Si to Ti-B to Ti-Al powder mixtures, irrespective of the differences in the thermodynamic characteristics of these syste ms. The differences in the mechanical properties of the reactants infl uence the shock-compression response (deformation or fracture and flow behavior) and mixing of reactants, and therefore, the configuration c hanges prior to initiation of shock-induced chemical reactions.