(中南大學 材料科學與工程學院， 長沙 410083)
摘 要: 利用X射線衍射、 掃描電鏡和倒置低頻扭擺儀研究了不同熱處理狀態(tài)Ti-50.8％Ni(摩爾分數(shù))合金的低頻阻尼性能。結(jié)果表明： 固溶處理試樣只存在馬氏體相變內(nèi)耗峰， 而時效處理試樣中既有馬氏體相變內(nèi)耗峰， 也發(fā)現(xiàn)有R相變內(nèi)耗峰，相變內(nèi)耗峰均對應(yīng)彈性模量極小值， 相變內(nèi)耗峰與頻率成反比； 在時效處理試樣中， 馬氏體相和R相的阻尼性能高于母相（B2)； 時效處理對馬氏體相變有抑制作用； 在400 ℃時效的TiNi合金中， 于200 K左右處發(fā)現(xiàn)內(nèi)耗峰， 隨著頻率的增加， 低溫內(nèi)耗峰向高溫方向運動，此內(nèi)耗峰與時效析出的Ti3Ni4粒子釘扎位錯有關(guān)， 用釘扎位錯脫釘?shù)腉-L模型解釋了低溫內(nèi)耗峰， 此內(nèi)耗峰的脫釘既包括機械脫釘， 也包括熱激活脫釘。
關(guān)鍵字: TiNi； 形狀記憶合金； 阻尼性能； 馬氏體相變； 內(nèi)耗
of Ti49.2Ni50.8 alloy
（Department of Materials Science and Engineering，
Central South University， Changsha 410083， China）
Abstract: The low-frequency damping capacities of Ti-50.8%Ni(molar fraction) alloy were investigated under different heat-treating conditions by XRD, SEM and low frequency inverted torsion pendulum. The results show that there is only damping peak of martensite transformation in solution treated specimen, and there are damping peak of martensite transformation and R phase transformation in 400 ℃ aged specimen. The damping peak of phase transformation corresponds to the minimum of elastic modulus and varies inversely with frequency. In the aged specimen, the internal friction of martensite phase or R phase are higher than that of parent phase(B2). The aged treatment impedes martensite phase transformation. The damping peak at 200 K of the 400 ℃ aged TiNi alloy moves to high temperature with increment of frequency. The damping peak relating with the Ti3Ni4 particle can be interpreted by unpinning process of pinned dislocation with G-L model. The unpinning process includes mechanical unpinning process and thermally activation unpinning process.
Key words: TiNi; shape memory alloy; damping capacity; martensitic transformation; internal friction
