Correlation between the cold-working and aging treatments in a Cu-15 wt pct Cr in situ composite

The cold-working and aging treatments are the two most important materials processing techniques used to produce the high strength and high conduct:ive Cu in situ composites. In this work, we systematically investigated the relationship between these mio techniques in a Cu-15 wt pet Cr in situ composite by means of the electrical conductivity measurement, hardness testing, tensile testing, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In contrast to the solution-treated samples, the cold working significantly improves the electrical conductivity but only produces a moderate hardening effect during the subsequent aging treatment. This is attributed to the rapid precipitation of incoherent Cr phases due to the high vacancy density in the Cu matrix after the cold deformation. At high aging temperature, the hardness and tensile strength of the material decreases significantly due to a pronounced process of recovery and recrystallization in the Cu matrix, as well as the recovery in the Cr fibers. When aged for 1 hour, an optimum aging temperature of 715 K is recommended.