Casting In-Situ Cu/CrBx Composites via Aluminum-Assisted Reduction

Abstract Chromium borides (CrBx) have been considered as promising strengthening phases for copper (Cu). However, traditional manufacturing methods such as powder metallurgy greatly restrict the sample size and part complexity. Here, we report that bulk Cu containing high volume percentages of uniformly distributed CrBx were fabricated by casting via in-situ reduction assisted by aluminum (Al). Two sets of precursors, i.e., borax-CuCr and KBF4-CrF3, were used and the respective reaction mechanisms were illustrated. In addition, the resultant in-situ particle morphologies and sizes from the precursors were studied. The use of KBF4-CrF3 generated smaller in-situ particles due to the less severe coalescence of particles. The microhardness of in-situ Cu/CrBx was significantly enhanced over pure Cu.