A. Terayama, Industrial Research Institute of Hiroshima Prefecture, Kure, Japan; H. Kyogoku, S. Komatsu, Department of Mechanical Engineering, School of Engineering, Kinki University, Higashihiroshima, Japan
Ti-Ni-Cu shape memory alloys were fabricated using Powder Metallurgy process.The elemental powders in chemical compositions of Ti49.8Ni50.2-xCux (x=0, 5, 10, 20) were mixed by planetary ball mill at 500 rpm for 0.3 ks and were sintered using pulse current sintering equipment. The influence Cu content of sintered alloys on tensile properties and shape memory properties were investigated. Ti49.8Ni50.2 alloy showed high tensile strength and elongation of 500MPa and 5%, respectively. Increase of Cu content provided narrower transformation hysteresis and lower yield stress. Constant load thermal cycling tests and differential scanning calorimetry curves show that the Ti49.8Ni40.2Cu10 alloy has the narrowest transformation hysteresis comparable to that of the wroght materials of 8 K, and the Ti49.8Ni30.2Cu20 alloy has clearly two-stage martensitic transformations.
Summary: The elemental Ti, Ni and Cu mixed powders were sintered using pulse current sintering equipment. The influence Cu content of sintered alloys on tensile properties and shape memory properties were investigated. Increase of Cu content provided narrower transformation hysteresis and lower yield stress. Ti49.8Ni40.2Cu10 alloy has the narrowest transformation hysteresis comparable to that of the wroght materials of 8 K, and the Ti49.8Ni30.2Cu20 alloy has clearly two-stage martensitic transformations.
