Mechanical properties of Rh-based L1₂ intermetallic compounds Rh₃Ti, Rh₃Nb and Rh₃Ta

A preliminary study of the mechanical properties of Rh-based Ll₂ intermetallic compounds Rh₃Ti, Rh₃Nb and Rh₃Ta is carried out by micro-vickers hardness tests at room temperature and compression tests at various temperatures ranging from room temperature to 1673 K. A cold-rolling test is also conducted on a Rh₃Ti plate. Although high temperature ductility-loss is observed in all compounds, Rh₃Ti shows good ductility at all temperatures investigated. Both Rh₃Nb and Rh₃Ta show a weak positive temperature dependence of strength (stress anomaly) at around 1273 K which is about half the melting point for both intermetallic compounds. The stress anomaly is discussed in terms of a phase stability concept based on the Kear-Wilsdorf (K-W) mechanism. High work hardening rates of Rh₃Nb and Rh₃Ta, which cause high vickers hardness at room temperature, are also attributed to the K-W mechanism.