Structural phase transformations in alloys of the Cu–Pt system during ordering

Abstract

Using the results of a Monte Carlo investigation, it is established that there are complicated structural phase transformations in the Cu–Pt system during cooling, which combine the order–disorder transitions and structural transformations. In the course of ordering, the high-temperature disordered fcc-phase can also undergo structural transformation. In the ordered state, a wide range of structures can be formed, depending on the alloy composition. In a few cases, there are closely spaced horizontal sections in the curve of the temperature dependence (in a certain temperature range) of the configurational energy. They correspond to different structural phase states of the system, with the energy difference being negligibly small. This is an indication of poor stability of these states to the structural phase transformations. In an approximation of thermodynamic probability of the occurrence of these states, in the case of finite temperatures we can expect them to co-exist in one and the same system or mutually transform under the action of a minimal thermal force.