Interrelation Between Strength, Flaw Size, Trasformability and R-Curve Behaviour in Fine-Grained (Mg,Y)-PSZ

A fine-grained (Mg,Y)-PSZ material using MgAl2O4 as grain boundary pinning agent has been developed. Eutectoid annealing treatments allow adjustment of the amount of transformable t-phase comparable to that of conventional Mg-PSZ. As a result, strong R-curve behavior and fracture toughness values of up to 11 MPa?m are observed. The strength of the fine-grained (Mg,Y)-PSZ with a grain size of 13 µm is controlled by isolated pores exceeding 40 µm in diameter. The interrelation between flaw size, transformability, R-curve behavior and strength is analyzed.