Debye temperature of nanocrystalline Zr_1—xAl_x solid solutions with different grain sizes

Abstract

In the Zr_1—xAl_x system a polymorphous crystal-to-glass transformation (CGT) has been found in earlier work. The CGT is characterized by a softening of the shear elastic constant as observed in both computer simulation and experiments. In this work we report studies of supersaturated Zr_1—xAl_x crystalline solid solutions with x = 0·1 and x = 0·16 which have been prepared by mechanical alloying or rapid quenching from the melt. From the specific heat measured at low temperatures, the Debye temperatures of the samples are calculated. A large reduction in the Debye temperature with decreasing grain size is found for both concentrations. It is concluded that the effect of grain size plays a major role in the elastic properties of the Zr_1—xAl_x solid solutions. The possibility of a local stabilization of the amorphous phase at the grain boundaries and the effect on the CGT is discussed.