나노재료 입계상의 소성변형에 대한 입계확산크립 모델

Abstract

In describing the deformation behavior of ultrafine-grained materials, a phase mixture model in which a polycrystalline material is regarded as a mixture of a crystalline phase and a grain boundary phase has been successful. The deformation mechanism for the grain boundary phase, which is necessary for applying the phase mixture model to polycrystalline materials, is modelled as a diffusional flow of matter along the grain boundary. A constitutive equation for the boundary diffusion creep of the boundary phase was proposed, in which the strain rate is proportional to (stress/grain size2). The upper limit of the stress of the boundary phase was set to equal to the strength of the amorphous phase. The proposed model can explain the strain size dependence of the strength of the grain boundary phase. Successful application of the model compared with published experimental data are described.