(陜西理工大學(xué) 材料科學(xué)與工程學(xué)院，漢中 723001)
摘 要: 對(duì)Ti-50.8Ni-0.1Zr(摩爾分?jǐn)?shù)，%)形狀記憶合金進(jìn)行了800 ℃固溶淬火+(300~600 ℃, 1~50 h)時(shí)效處理，采用光學(xué)顯微鏡、透射電鏡和差示掃描量熱儀研究了時(shí)效溫度和時(shí)效時(shí)間對(duì)該合金顯微組織和相變行為的影響。結(jié)果表明：隨時(shí)效溫度升高，合金中Ti3Ni4析出相由細(xì)小顆粒狀生長(zhǎng)為透鏡狀再變?yōu)榇制瑺睢?00 ℃時(shí)效態(tài)合金的相變類(lèi)型為A→R→M/M→R→A(A為母相B2，CsCl型結(jié)構(gòu)；M為馬氏體B19′，單斜結(jié)構(gòu)；R為R相，菱方結(jié)構(gòu))，400 ℃時(shí)效態(tài)合金的相變類(lèi)型由A→R→M/M→R→A向A→R→M/M→A型轉(zhuǎn)變，500 ℃和600 ℃時(shí)效態(tài)合金的相變類(lèi)型分別為A→R→M/M→A和A→M/M→A。隨時(shí)效溫度升高，該合金的R、M相變溫度先升高后降低，400 ℃、50 h時(shí)效態(tài)合金的R相變溫度最大(為43.7 ℃)，500 ℃、50 h時(shí)效態(tài)合金的M相變溫度最大(為4.0 ℃)；M相變熱滯在26.1~122.6 ℃之間變化；R相變熱滯比較穩(wěn)定，在4.8~7.5 ℃之間變化。隨時(shí)效時(shí)間延長(zhǎng)，該合金的R、M相變溫度先升高后趨于穩(wěn)定，M相變熱滯先降低后趨于穩(wěn)定，R相變熱滯變化不大。時(shí)效溫度對(duì)Ti-50.8Ni-0.1Zr合金析出相形貌和相變行為的影響比時(shí)效時(shí)間更顯著。
關(guān)鍵字: Ti-50.8Ni-0.1Zr合金；形狀記憶合金；時(shí)效工藝；顯微組織；相變行為
（School of Materials Science and Engineering, Shaanxi University of Technology, Hanzhong 723001, China）
Abstract:The heat treatments of solution-quenched at 800 ℃ + aged at 300-600 ℃ for 1-50 h were carried out in Ti-50.8Ni-0.1Zr (mole fraction) shape memory alloy, the effects of aging temperature and aging time on the microstructure and phase transformation behaviors of the alloy were investigated by optical microscopy, TEM, and differential scanning calorimetry. With the increase of aging temperature, the morphologies of Ti3Ni4 precipitates in the alloy change from the fine particle to the lenticular, and then to the thick plate. The phase transformation type of the alloy aged at 300 ℃ is A→R→M/M→R→A (A—Parent phase B2, CsCl; M—Martensite B19′, monoclinic; R—R phase, rhombohedral), the transformation type of the alloy aged at 400 ℃ changes from A→R→M/M→R→A to A→R→M/M→A; the transformation types of the alloy aged at 500 ℃ and 600 ℃ are A→R→M/M→A and A→M/M→A, respectively. With the increase of aging temperature, the R and M phase transformation temperatures of the alloy increase first and then decrease, and the maximum values 43.7 ℃ and 4.0 ℃ are obtained in the alloys aged at (400 ℃, 50 h) and (500 ℃, 50 h), respectively. The temperature hysteresis of M phase transformation changes in the range of 26.1-122.6 ℃. The temperature hysteresis of the R phase transformation is stable and changes in the range of 4.8-7.5 ℃. With the increase of aging time, the R and M phase transformation temperatures of the alloy increase first and then tend to be stable, the temperature hysteresis of the M phase transformation decreases first and then tends to be stable, and the change of the temperature hysteresis of the R phase transformation is small. The effects of aging temperature on the precipitate morphology and phase transformation behaviors of Ti-50.8Ni-0.1Zr alloy are greater than that of the aging time.
Key words: Ti-50.8Ni-0.1Zr alloy; shape memory alloy; aging process; microstructure; phase transformation behavior
