Ultrafast Solid-State Reactions and Martensitic Transformations in Thin Films

摘要

Ultrafast transformations and solid-state reactions are attracting constant current interest. In particular, shock-induced solid-state synthesis is responsible for the formation of reaction products with sizes d = 10 - 100 μm in τ = 10~(-5) - 10~(-7) s [1-4]. This corresponds to the extremely overestimated effective diffusion coefficient D_(eff) ～ d~2/4τ = 10~(-1) - 10~(-5) m~2/s and contradicts the slow diffusion mechanism, which is the single explanation of mass transfer in the solid state. Various concepts in the framework of the diffusion mechanism were proposed to explain a high mobility of atmos in ultrafast synthesis. Disregarding the structure mechanism, Thadhani et al. [4] assumed for the first time that diffusionless cooperative processes must dominate in synthesis during the action of a shock wave. This assumption implies that mutual mass transfer responsible for the mixing of reagent atoms proceeds with velocity V_r ～1-1000 m/s.