Mechanistic study of shock-induced solid-state chemistry in Ti- and Ta-based carbide and boride systems

Abstract

Shock chemistry were performed on mixtures of Ti‐C, Ti‐B, Ta‐C, and Ta‐B powders, to study the effects of density differential amongst the powder mixture constituents, in all systems with otherwise very high heats of reaction. The experiments were performed at a wide range of shock conditions, using the the Sandia Bear fixtures and the CETR/Sawaoko 12‐capsule plate‐impact system, to establish the reaction threshold for respective systems. It was observed that the density differential between the constituents, and the heat of reaction do not significantly affect the reaction threshold. Instead, the propensity for reaction increases with increasing degree of mixing of constituents either by simultaneous deformation or fracture. In this paper we present the microscopic and macroscopic characteristics of the shock compressed compacts to delineate the mechanistic processes influencing shock‐induced chemical reactions in Ti‐ and Ta‐based carbide and boride forming powder mixtures.