Pressure Dependence of the CsCl-Type Order-Disorder Transition Temperature of δ-VMn Alloy

Abstract

The order-disorder transition temperature of an equiatomic δ–VMn superlattice was measured at pressures of up to 30 kbar by a Kennedy-type piston cylinder high pressure apparatus and differential thermal analysis. The value of dT_c⁄dP for an equiatomic δ–VMn superlattice was found to be 2.3∼2.5 deg/kbar, which is larger than those of β–CuZn and α–FeCo.
The values of dT_c⁄dP of β–CuZn, α–FeCo and δ–VMn were estimated theoretically from the equations of Clapeyron-Clausius and of Ehrenfest, and these values were compared with the experimental results. A brief discussion was made on the differences between the theoretical and the experimental values.