(1. 陜西理工大學(xué) 材料科學(xué)與工程學(xué)院，漢中 723001；
2. 陜西理工大學(xué) 圖書館，漢中 723003)
摘 要: 利用XRD、示差掃描熱分析儀(DSC)、光學(xué)顯微鏡和拉伸試驗研究退火態(tài)Ti-50.8Ni-0.5V(摩爾分?jǐn)?shù)，%)形狀記憶合金的相變行為、組織特征和力學(xué)性能。結(jié)果表明：400~700 ℃退火態(tài)Ti-50.8Ni-0.5V合金室溫組成相為母相B2和馬氏體B19′。隨退火溫度升高，該合金冷卻/加熱時的相變類型由B2→R/R→B2型向B2→R→B19′/B19′→R→B2型向B2→R→B19′/B19′→B2型向B2→B19′/B19′→B2型轉(zhuǎn)變；R相、馬氏體相變溫度先升高后降低，極大值28.1 ℃、?58.5 ℃分別在400 ℃、500 ℃退火態(tài)合金中取得；顯微組織由纖維狀變?yōu)榈容S狀，再結(jié)晶溫度在550~600 ℃之間；抗拉強(qiáng)度降低，塑性提高；應(yīng)力誘發(fā)馬氏體臨界應(yīng)力σM先降低后升高，極小值325 MPa在450 ℃退火態(tài)合金中取得；殘余應(yīng)變先升高后降低再升高，極大值2.55%在450 ℃退火態(tài)合金中取得，極小值0.65%在500~650 ℃退火態(tài)合金中取得。隨形變溫度升高，合金由形狀記憶效應(yīng)(SME)向超彈性(SE)轉(zhuǎn)變，SME→SE轉(zhuǎn)變溫度可用DSC曲線上馬氏體逆相變峰溫度tMr+16 ℃估算。隨循環(huán)次數(shù)增加，400 ℃退火態(tài)合金的σM穩(wěn)定，500和600 ℃退火態(tài)合金的σM先降低后趨于穩(wěn)定。
關(guān)鍵字: Ti-Ni-V合金；形狀記憶合金；相變；形狀記憶效應(yīng)；超彈性
（1. School of Materials Science and Engineering, Shaanxi University of Technology, Hanzhong 723001, China;
2. Library, Shaanxi University of Technology, Hanzhong 723003, China）
Abstract:The phase transformation behaviors, microstructure characteristics and mechanical properties of Ti-50.8Ni-0.5V (mole fraction, %) shape memory alloy were studied by XRD, differential scanning calorimetry (DSC), optical microscope and tensile test. The results show that the constituent phases at room temperature of Ti-50.8Ni-0.5V alloys annealed at 400-700 ℃ are parent phase B2 and martensite B19′. With the increase of the annealing temperature, the phase transformation type of the alloy changes from B2→R/R→B2 to B2→R→B19′/B19′→R→B2 to B2→R→ B19′/B19′→B2 to B2→B19′/B19′→B2 upon cooling/heating. The R, martensitic transformation temperatures of the alloy increase first and then decrease, and the maximum 28.1 ℃, -58.5 ℃ are obtained in the alloys annealed at 400 ℃ and 500 ℃, respectively. The microstructure of the alloy changes from fibrous to equiaxed, and the recrystallization temperature of the is among 550-600 ℃. The strength of extension decreases and the plasticity increases in the alloy. The critical stress for inducing martensitic transformation (σM) of the alloy decreases first and then increases, and the minimum 325 MPa of σM is obtained in the alloy annealed at 450 ℃. The residual strain increases first and then decreases and then increases, the maximum 2.55% and 1.84% are obtained in the alloys annealed at 450 ℃ and 700 ℃, respectively, and the minimum 0.65% is acquired in the alloys annealed at 500-650 ℃. With the increase of the deforming temperature, a transformation of shape memory effect (SME)→ superelasticity (SE) occurs in annealed Ti-50.8Ni-0.5V alloy, and the SME→SE transformation temperature can be approximately estimated by tMr+16 ℃ (tMr is the peak temperature of the martensitic reverse transformation in DSC curve). With the increase of the cyclic number, the σM of the alloy annealed at 400℃ is stable, and the σM of the alloys annealed at 500 and 600 ℃ decreases first and then tend to be stable.
Key words: Ti-Ni-V alloy; shape memory alloy; phase transformation; shape memory effect; superelasticity
