Phase Transformations in Equiatomic Y–Cu Powder Mixture at Mechanical Milling

Abstract

Mechanical alloying of the elemental powder mixture of copper and yttrium is performed in a high-energy planetary ball mill. The equiatomic YCu compound with full ordered CsCl-type structure is synthesized by use of powdermetallurgy methods for the first time. Phase transformations taking place at Y-Cu mixture milling are studied by x-ray diffraction methods. An expanded description of original software package for the automated DRON apparatus is presented. This software is used for analysis and interpretation of the obtained x-ray diffraction data. This package is intended for solving different tasks, namely: determination of both peak positions and integral intensities of the Bragg reflections by means of full profile analysis; carrying out the qualitative and quantitative phase analyses using PDF (Powder Diffraction File) data for phase identification and the least square method for lattice-constants' refinement; testing the structure models and refining crystal-structure parameters (including coordinates, atomic position filling, texture, etc.). The effect of oxygen on the phase composition of milling products is analysed. As revealed, the mixture of two oxides (Y 2 O 3 and YCuO) is forming at the last stage of the milling in the air. So, the phase transformation during milling of the equiatomic Y-Cu charge in the air follows the reaction Y Cu YCu YCu 2 YCu 2 O 2 Y 2 O 3 YCuO YCu 5 . Only the first stage of this transformation is realized in the case of synthesis under