Microstructure and mechanical properties of as-cast Ti-Ni-Fe alloys

Microstructure and mechanical properties of as-cast Ti-Ni-Fe alloys were investigated. The experimental results show that the microstructures of Ti49Ni50.5Fe0.5 and Ti49Ni50Fe1 alloys are composed of the TiNi with body-centered cubic (BCC), Ti2Ni and Ti3Ni4 phases; the microstructures of Ti49Ni49Fe2 and Ti49Ni48Fe3 alloys are composed of the BCC TiNi and Ti2Ni phases. With the increase of Fe content, the precipitation of Ti3Ni4 phase is inhibited, the contents of Ti2Ni phase are also reduced, and the contents of correspondingly TiNi phase increase. The Ti49Ni49Fe2 and Ti49Ni48Fe3 alloys with high yield strength and fracture strength can consider as engineering materials with excellent mechanical properties. In addition, the Ti-Ni-Fe alloys with low elastic modulus can be used as hard tissue implants of biomedical alloys. Based on observing the fracture morphology, the cleavage fracture of the four alloys demonstrates that the TiNi matrix phase is body-centered cubic structure, and is not simple cubic structure.