Microstructure and mechanical properties of NiTi-Al based alloys with addition of Fe

The influences of Fe on the microstructure and mechanical properties of Ni-43Ti-4Al-2Nb-2Hf-xFe (x=0, 1, 3, 5 at-%) alloys were investigated, prepared by vacuum non-consumable arcmelting method. The results show that the microstructure of the alloys is refined gradually with increasing Fe content. The appropriate addition of Fe produces an improvement of the tensile strength and ductility of the alloy. The highest tensile strength and elongation of the study's alloys was seen with the 3 at-%Fe addition, resulting in strength and elongation of up to 1308 MPa and 4·15%. The fracture characterisation changes from a quasi-cleavage fracture to a mixed fracture of quasi-cleavage and dimple. Further increasing the Fe content to 5 at-%, the mechanical properties deteriorated.