Gold-Alloy Electrodeposits—Phase and Microstructural Changes Induced by Heat Treatment as Revealed by X-Rays

Abstract

Changes in composition and microstructure of gold‐alloy electrodeposits caused by thermal treatment at relatively low temperatures, 100°–500°C, are revealed by semiquantitative x‐ray diffraction analysis. The metallurgical characteristics of gold‐nickel and gold‐cobalt plates deviate from known equilibria shown by the temperature‐composition or phase diagrams of the thermally alloyed systems. The plates as deposited are essentially single phase, metastable supersaturated, solid solutions. Thermal treatment of the Au‐Ni plate causes precipitation of a Ni‐rich phase; the precipitates of the Au‐Co plate are practically pure, allotropie modifications of Co.