Papers by Author: I.S. Sandhu

Abstract: Tracer di f fusion by way of vacancies is invest igated in B2 intermetal l ics AB by means of a kinet ic equat ion approach. The model used is one wi th four inter sub-lat t ice frequencies where each sub-lat t ice is t reated as a random al loy. Coupl ing is achieved between the two types of cycles, i .e. , wi th the vacancy start ing on one sub- lat t ice and finishing on ei ther sub-lat t ice and wi th a vacancy start ing on the other sub-lat t ice and finishing on ei ther sub-lat t ice. An expression for the t racer cor relat ion factor is derived in terms of atom vacancy exchange frequencies and atomic concentrat ions. Resul ts from this expression are compared wi th Monte Car lo calculat ions and also resul ts f rom a previous Manning-type random al loy approach to the problem.

Abstract: In this paper Manning random alloy model has been extended to the binary nonstoichiometric intermetallic compound of the B2 structure. Two sub-lattices, that are dynamically independent in six-jump cycle (6JC) mechanism, are coupled together by taking into consideration the vacancy motion as a sequence of nearest neighbour jumps in random directions. The linear response expressions for the phenomenological transport coefficients are evaluated making use of the kinetic equation approach. The expressions for collective correlation factors are derived in terms of the equilibrium partial atomic concentrations and jump frequencies. Results are compared with Monte Carlo simulation results using the four-frequency model.