Effect of Fe Addition on Microstructure and Mechanical Properties of As-cast Ti₄₉Ni₅₁ Alloy

Effect of Fe addition on microstructure and mechanical properties of as-cast Ti₄₉Ni₅₁ alloy were investigated. The experimental results shows the microstructures of Ti_48.5Ni₅₁Fe_0.5 and Ti₄₈Ni₅₁Fe₁ alloys are mainly composed of TiNi matrix phase (body-centered cubic, BCC), Ti₃Ni₄ and Ni_2.67Ti_1.33 phases; the microstructure of Ti₄₇Ni₅₁Fe₂ alloy is mainly composed of BCC TiNi, Ti₃Ni₄, Ni_2.67Ti_1.33, and Ni₃Ti phases; the microstructure of the Ti₄₅Ni₅₁Fe₄ alloy is mainly composed of TiNi, Ti₃Ni₄ and Ni₃Ti phases. The Ni₃Ti nanocrystalline precipitates at the adjacent position of Ni_2.67Ti_1.33 phase. The Ti_48.5Ni₅₁Fe_0.5 and Ti₄₈Ni₅₁Fe₁ alloys have high yield strength and fracture strength, and can be as the engineering materials with excellent mechanical properties. In addition, the Ti_48.5Ni₅₁Fe_0.5 alloy with the low elastic modulus and large elastic energy is also a good biomedical alloy of hard tissue implants. The fracture mechanism of the four alloys is mainly cleavage fracture or quasi-cleavage fracture, supplemented by ductile fracture. The experimental data obtained provide the valuable references in application of as-cast alloys and heat-treated samples in the future.