Effect of friction-stir processing and subsequent aging treatment on microstructure and service properties of cu-Cr-Zr alloy

Abstract

The effect of friction-stir processing (FSP) and the subsequent aging treatment on the microstructure, electrical conductivity, and mechanical properties of a Cu-0.3%Cr-0.5%Zr alloy was studied. FSP promoted complex microstructural changes, including significant grain refinement and dissolution of secondary particles within the stir zone and particle coarsening within the heat-affected zone. The particle phenomena resulted in the essential material softening and degradation of electrical conductivity. The subsequent aging treatment provided particle reprecipitation within the stir zone and thus essentially recovered material properties in this area. In the heat-affected zone, however, the recovery effect was less pronounced, thus leading to the characteristic W-shaped profiles of microhardness and electrical conductivity. This result was attributed to the insufficient degree of supersaturation of the solid solution in this microstructural region, which, in turn, promoted the relatively slow precipitation kinetics.