Microstructures and Mechanical Properties of Annealed Ti₅₀Ni₄₇Fe₃ Shape Memory Alloy

Abstract

The effect of annealing temperature on the microstructures and mechanical properties of Ti50Ni47Fe3 (at. %) shape memory alloy was investigated by using a cold-rolled alloy sheet. For this purpose, a scanning electron microscope, electron backscatter diffraction, a transmission electron microscope, X-ray diffraction, tensile tests and Vickers hardness tests were used. The evolution of the microstructures, mechanical properties and fracture morphology of Ti50Ni47Fe3 alloy was studied. The results show that the recovery occurs at an annealing temperature of 500 °C, and the recrystallization occurs at 600 °C. Because of the recrystallization at 600 °C, the //RD texture disappears, and the intensity of the //RD texture decreases; the alloy reaches its maximum elongation while maintaining a high strength, and at this annealing temperature, the alloy has excellent comprehensive mechanical properties. After the temperature exceeds 600 °C, the mechanical properties of the alloy decrease sharply. With the increase of the annealing temperature, the quantity and distribution of elliptical Ti2Ni-phase particles show almost no specific changes. Additionally, with the increase of annealing temperatures to 600 °C, the fracture surface of Ti50Ni47Fe3 alloys becomes flatter.

Keywords

• TiNiFe alloy
• shape memory alloy
• mechanical properties
• recrystallization
• fracture