Crystallization Phases of the Zr41Ti14Cu12.5Ni10Be22.5 Alloy After Slow Solidification

Abstract

A systematic study was carried out on the equilibrium phases after slow solidification of the Zr41Ti14Cu12.5Ni10Be22.5 alloy. The crystalline microstructure of the slowly cooled melt of the alloy shows “polygons” and “plates” embedded in a fine-grained two-component matrix. To analyze the crystal structure of the different components, microdiffraction technique combining convergent beam electron diffraction and conventional selected-area electron diffraction were used. The stoichiometry of these phases was confirmed by field ion microscopy with atom probe and energy-dispersive x-ray analysis in a transmission electron microscope. The polygons were determined to be cubic (a = 1.185 nm) with space group Fm3m (cF116). The plates were found to be tetragonal (a = 0.37 nm, c = 1.137 nm) with space group I4/mmm (tI6). Its composition is (Cu + Ni)(Zr + Ti)2. One phase of the fine-grained two-component matrix was rich in Ti and poor in Be; the other one was rich in Be and poor in Ti. The Ti-rich phase was determined to be hexagonal (a = 0.536 nm, c = 0.888 nm) with space group P63/mmc.