A mathematical model was developed for accelerated solid-state diffusion during mechanical alloying in a binary substitutional system. An individual lamellar particle, formed due to fracturing/cold-welding during a preliminary stage of mechanical alloying, was considered. Interdiffusion occurred via the vacancy mechanism. During plastic deformation, jog-dragging by moving screw dislocations generated non-equilibrium vacancies and interstitials which could diffuse, interact with edge dislocations and recombine. In order to evaluate the point-defect generation rate, a simple Hirsch-Mott theory was used. Numerical simulations were performed for repeated deformation and rest cycles at 100C; using realistic parameter values. The effect of non-equilibrium vacancies upon atomic diffusion revealed itself via an increase in the partial diffusivities of substitutional atoms, and via cross-link terms in the matrix of interdiffusion coefficients. The incoherent phase boundary between the pure elements was considered to be a sink for non-equilibrium vacancies. Substantial alloying, via solid-state diffusion, was observed after some 4000s of mechanical alloying.

Modelling Accelerated Solid-State Diffusion under the Action of Intensive Plastic Deformation. B.B.Khina, I.Solpan, G.F.Lovshenko: Journal of Materials Science, 2004, 39[16-17], 5135-8