K. Udoh

Two types of checkerboard-like microstructures in Au–Cu–Pd ternary alloys

Abstract The phase transformation process in Au–Cu–Pd ternary alloys with the compositions within or near the two-phase region (Au 3 Cu+AuCu I) was studied by means of transmission electron microscopy and hardness testing. Two types of characteristic checkerboard-like microstructures were observed: (1) the coexistence of the Au 3 Cu and AuCu I ordered phases, and (2) the coexistence of the AuCu I ordered phase and disordered phase with face-centered cubic structure. Different age-hardening behaviors were recognized: The high hardness value in the former was maintained for prolonged aging periods, and that produced in the latter was maintained to a certain period followed by over-aging.

Coherent phase diagram of Au-Cu-Pd ternary system near and within the two-phase region of Au3Cu and AuCu I ordered phases

Abstract Phase identification and analysis of microstructural configuration were done by transmission electron microscopy to determine the coherent phase diagram of the Au–Cu–Pd ternary system near and within the two-phase region of the Au 3 Cu and AuCu I phases. Six distinguishable regions were found in the present experimental phase diagram: a single-phase region of the disordered solid solution, α; a single-phase region of the Au 3 Cu ordered phase; a single-phase region of the AuCu I ordered phase; a region of the coexisting Au 3 Cu and AuCu I ordered phases; a region of the coexisting Au 3 Cu and α phases; and a region of the coexisting AuCu I and α phases.