Microstructure and room temperature mechanical properties of Ni ₃Si based alloy with titanium addition

The microstructure and room temperature mechanical properties of Ni-15Si-2Nb-1Cr-3Ti-0.2B alloy were investigated by means of X-ray diffraction, scanning electron microscopy, electron probe microanalysis, transmission electron microscopy and tensile test in air and vacuum. The results of tensile testing revealed that the addition of Ti can significantly improve the elongation as well as ultimate tensile strength (18.3% and 1320 MPa in air and 21% and 1600 MPa in vacuum) in comparison with the Ni-18Si-3Nb-1Cr-0.2B base alloy (10% and 1130 MPa in air and 14% and 1240 MPa in vacuum) at room temperature. In addition, the fracture surface of the specimen after tensile test presents a typical transgranular ductile mode, with a fully dimpled fracture pattern. This indicates that the addition of Ti in the Ni-15Si-2Nb-1Cr-3Ti-0.2B alloy can effectively suppress the environmental embrittlement at room temperature. In addition, the Ni-15Si-2Nb- 1Cr-3Ti-0.2B alloy exhibits insensitivity to strain rate in both air and vacuum at room temperature.