(1. 陜西理工大學 材料科學與工程學院，漢中 723001；
2. 陜西理工大學 圖書館，漢中 723003)
摘 要: 用XRD、光學顯微鏡、示差掃描量熱儀和拉伸實驗研究退火溫度(ta)對冷拉Ti-50.8Ni-0.1Nb(摩爾分數(shù)，%)合金組織、相變和形狀記憶行為的影響。結(jié)果表明：350~700 ℃退火態(tài)Ti-50.8Ni-0.1Nb合金由馬氏體M(B19′，單斜結(jié)構(gòu))和母相A(B2，CsCl型結(jié)構(gòu))組成。隨ta升高，合金組織形貌由纖維狀變?yōu)榈容S狀，再結(jié)晶溫度約為580 ℃；合金冷卻/加熱相變類型由A→R→M/M→R→A型向A→R→M/M→A型向A→M/M→A型轉(zhuǎn)變(R-R相，菱方結(jié)構(gòu))，R相變溫度降低，M相變溫度和熱滯先升高后降低，R相變熱滯為6.7~9.8 ℃。350~550 ℃退火態(tài)合金的抗拉強度高于600~700 ℃退火態(tài)合金的，伸長率則遠低于后者的。400~550 ℃退火態(tài)合金呈形狀記憶效應(yīng)，350 ℃退火態(tài)和600 ℃及以上溫度退火態(tài)合金呈超彈性。隨應(yīng)力-應(yīng)變循環(huán)次數(shù)增加，合金應(yīng)力-應(yīng)變曲線的平臺應(yīng)力下降。400~550 ℃退火態(tài)合金的形狀記憶效應(yīng)和600 ℃及以上溫度退火態(tài)合金的超彈性穩(wěn)定性良好。
關(guān)鍵字: Ti-Ni-Nb合金；形狀記憶合金；退火；相變；形狀記憶行為
（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 effects of annealing temperature (Ta) on the microstructure, phase transformation and shape memory behavior of cold drawing Ti-50.8Ni-0.1Nb (mole fraction, %) shape memory alloy were investigated by XRD, optical microscopy, differential scanning calorimetry and tensile test. The results show that the phase compositions of Ti-50.8Ni-0.1Nb alloy annealed at 350-700 ℃ are martensite M (B19′, monoclinic) and parent phase A (B2, CsCl). With increasing Ta, the microstructure morphology of the alloy changes from fibrous to equiaxed grain, the recrystallization temperature is about 580 ℃; the transformation types of the alloy change from A→R→M/M→R→A to A→R→M/M→A to A→M/M→A (A-parent phase B2, CsCl; R-R phase, rhombohedral; M-martensite B19′, monoclinic) upon cooling/heating, the R transformation temperature of the alloy decreases, the M transformation temperature and temperature hysteresis increases firstly and then decreases, the R transformation temperature hysteresis is 6.7-9.8 ℃. The tensile strength of the alloy annealed at 350-550 ℃ is higher than that of the alloy annealed at 600-700 ℃, while the percentage elongation of the former is lower than that of the latter. The alloy annealed at 400-550 ℃ shows shape memory effect, and the alloys annealed at 300 ℃ and 600-700 ℃ show superelasticity. With increasing stress-strain cycling number, the platform stress in the stress-strain curve of the alloy decreases. The stability of the shape memory effect in the alloy annealed at 400-550 ℃ and the superelasticity in the alloy annealed at 600-700 ℃ are well.
Key words: Ti-Ni-Nb alloy; shape memory alloy; annealing; transformation; shape memory behavior
