Characterization and TEM Observation of Microstructures of Zr Added Cu–3%Ag Alloys

Abstract

In this study, Zr (0.1, 0.2, 0.3 mol%) was added to a Cu–3 mol% Ag alloy, and prepared by mold casting. Homogenization treatment was conducted at 900°C for 18 ks. Hot and cold rolling were subsequently conducted. The alloys were solution treated at 850°C for 3.6 ks, quenched into water and subsequently aged at 450°C for up to 345.6 ks. Micro–Vickers hardness and electrical conductivity were measured. Tensile tests were conducted on as–solution treated alloys and peak aged alloys. X–ray diffraction (XRD) analysis, optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM) observations were carried out for the solution treated and aged alloys.

Zr addition resulted in the increase of peak hardness with less than decrease of 10%IACS in electrical conductivity. Primary particles of Cu₄AgZr was observed after casting, which resulted in grain refinement. After the solid solution treatment, mainly Ag and small amounts of Zr were dissolved into the matrix. TEM observation and XRD analysis were conducted both on the alloys and extracted precipitates. Ag precipitated during aging. In the aged samples, Zr oxide was also observed besides Ag precipitates.