Existence and Formation of LPAPB Structures in Pt₃V Studied Using High Resolution Electron Microscopy

Abstract

In recent years microstructural studies of ordered binary alloys have gained renewed attention due to the quest for adequate test systems for different calculation methods that seek to determine the phase diagram or at least the ordered ground state structures for a given system or for a set of different systems. A few examples are the Cu-Pd [1], Al-Ti [2] and Al-Mg [3] systems as described by the ANNNI model [4], the Cu-Au system as studied using the cluster variation method (CVM) [5], and different transition metal alloys (TMA) such as Pt-Ti [6,7] and Pt-V [7,8] investigated in terms of the generalized perturbation method (GPM) [9,10]. Since in many of these ordered alloys the separation between the stability regions of different micro structures with respect to composition, homogeniety and temperature is very crucial for the relation with the various calculations, a number of different experimental techniques, macroscopical as well as microscopical, have been applied. Here the high resolution electron microscopy (HREM) technique is a very powerful tool that can be used to solve different problems, such as the unravelling of complex diffraction patterns resulting from many different orientation variants and multiphase situations [11], the study of microstructural defects such as anti-phase boundaries (APB) and of several transformation mechanisms between different ordered structures down to the atomic level [8,12].