Effect of chromium addition on the copper binder structure, properties and adhesion to diamond

The study covers the effect of chromium on the structure, mechanical properties, and adhesion of alloys used as a binder for metal-diamond composites. Cu–Cr powder mixtures were obtained by high-energy ball milling in a planetary centrifugal mill. This process was used to obtain two-phase Cu–Cr powders with uniformly distributed submicron Cr particles. Cu–Х%Cr compact samples (where Х = 10, 30 and 50 %) were obtained by hot pressing. It was found that Cu–30%Cr compact samples showed the best mechanical properties (9 times higher as compared to pure copper). These alloys feature a hardening mechanism based on the Hall–Petch law. The resulting alloys have a homogenous ultrafine structure, which results in high ultimate bending strength (2330 MPa). Chromium addition to the copper binder considerably increases its adhesion to diamond in metal-diamond composites due to chemical interaction between chromium included into the binder and diamond carbon with Cr3C2 carbide formation.