Cu substion for Ni in Ti50Ni50-XPdX ( X=20∼30 at％) HTSMAs

• Main Authors: Han-Yun Chang, 張瀚云
• Other Authors: 吳錫侃
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/25465710535028513631

碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 94 === Transformation temperature and latent heat of Ti50(Ni, Cu)50-xPdx （x：20 ~ 30 at％）high temperature shape memory alloys（SMAs）are studied. In addition, annealing effect on transformation behavior and microstructure of cold-rolled Ti50(Ni, Cu)50-xPdx SMAs is also studied. Ti50(Ni25-yCuy)Pd25 and Ti50(Ni30-zCuz)Pd20 SMAs both exhibit one-stage B2←→B19 transformation, and their Ms and ΔH increase with increasing the Cu substitution. Severely cold-rolled and 650℃ annealed Ti50(Ni15Cu15)Pd20 and Ti50(Ni15Cu10)Pd25 alloys induce precipitates in the matrix. The precipitates increase their size with prolonging annealing time and deteriorates the alloys’ shape memory effec（t SME）. The composition of the precipitates is identified as (Ti,Cu)2(Pd,Ni) by EDX test. The precipitates of 25％cold-rolled and 500℃annealed Ti50(Ni25Cu5)Pd20 are too small to be observed in SEM. However, Ti50(Ni15Cu10)Pd25 and Ti50(Ni25Cu5)Pd20 SMAs cold-rolled and annealed at 650℃ and 800℃, respectively, show no precipitate and good SME. Among all Ti50(Ni, Cu)50-xPdx SMAs, Ti50(Ni25Cu5)Pd20 SMA with 25％ cold rolling and 500℃×10min annealing 10 mins exhibits the best SME.