Annealed CoCrFeNi-Mo alloys show high tensile strength and no serious embrittlement occurred, although precipitation of the sigma phases, which are of concern for brittleness. However, tensile properties of as-cast CoCrFeNi-Mo alloys are currently not perfectly clarified, especially at low temperatures.
Tensile tests of as-cast CoCrFeNi-Mo alloys (Mo at 4.9, 7.5, and 9.0 at%) were performed at room temperature and liquid nitrogen temperature. The as-cast specimens showed ruptured before plastic deformation occurred for the 7.5 at% Mo and 9.0 at% Mo alloys at both room temperature and liquid nitrogen temperature. These ultimate tensile strength were about 300 MPa. The 4.9at%Mo specimens at room temperature showed tensile strength of 645 MPa and elongation of 36.2%, and tensile strength of 934 MPa and elongation of 21.2% at liquid nitrogen temperature, suggesting that the high ductility at liquid nitrogen temperature was due to twin-induced plasticity.