A new dislocation-punching model, based upon Eshelby's approach, was proposed for a functionally graded material which was subjected to a temperature change. The functionally graded material, consisting of several layers, was imagined to be deposited onto a ceramic substrate. Two types of layer microstructure were considered. One consisted of a metal matrix and ceramic particles, and the other consisted of a ceramic matrix and metal particles. The elastic energy was evaluated for the situation where plastic strain as well as thermal mismatch strain was introduced into the metal phase. The work which was dissipated during plastic deformation was also calculated. By applying the condition that the reduction in elastic energy was greater than the work dissipated, the critical thermal mismatch strain which was required in order to induce stress relaxation was determined. The magnitude of the plastic strain when relaxation occurred was also determined.

Dislocation Punching from Interfaces in Functionally-Graded Materials. M.Taya, J.K.Lee, T.Mori: Acta Materialia, 1997, 45[6], 2349-56