Diffusion and stresses in multiphase solids

Stresses generated during mutual diffusion will influence the growth rate of new phases. There are experimental evidences for pronounced stress effects in mutual diffusion couples especially in the so-called closed geometry. Theoretical description is difficult even in a two component system because besides the equations describing material transport and stress development one must deal with moving phase boundaries in the diffusion zone. After an overview of the interrelation of stress and diffusion the basic equations are presented. Next the way of implementing the above formulation in a simulation program is described. The effect of the phase growth on the stress development is shown through the calculation results for various mass transport conditions. Maxwell-type creep behaviour (plastic flow) was assumed and the calculations were performed with the assumption that the material properties are concentration independent. All results in this paper refers to incoherent phase boundaries, where stress relaxation is allowed.