二重不均質介在物とその応用 : 第 2 報応力誘起変態による PSZ の靱性増加の解析

抄録

In a partially stabilized zirconia (PSZ) containing tetragonal ZrO₂ particles, a crack may be closed due to dilatational transformation strain of the particles induced in both a process zone and its wake surrounding the crack by enhanced stress at the vicinity of the tip of crack. In this study, micromechanical analysis on the toughness of such a PSZ is performed by modeling a crack surrounded by a process zone and its wake as a mixed double inclusion of the first kind which is defined in the previous paper as an ellipsoidal inhomogeneous inclusion surrounded by an annular inclusion. Energy release rate of the crack G in the PSZ is derived and then its decrease ΔG due to stress induced transformation of particles is formulated as a function of the transformation strain, the thickness of zone wake, and the volume fraction of particles. Numerical results of ΔG is good agreement with the experimental ones obtained by Swain et al.