Ti-51.1Ni形状记忆合金相变和低温形变特性

Characteristics of transformation and low-temperature deformation of Ti-51.1Ni shape memory alloy

摘要:

用示差扫描量热仪(DSC)和拉伸试验研究了退火温度对形变处理态Ti-51.1Ni(原子分数, %)形状记忆合金相变和低温形变特性的影响。结果表明,随退火温度升高,合金冷却 / 加热时相变类型由A→R / M→R→A型向A→R→M / M→R→A型再向A→R→M / M→A(A-母相B2,R-R相,M-马氏体相)型转变,R相变温度和M相变热滞降低,M相变温度升高,R相变热滞变化不大,保持在6.5 ℃左右。在10 ℃变形时,400~550 ℃退火态合金呈现形状记忆效应(SME)+超弹性(SE)特性,600~700 ℃退火态合金呈现SE特性,随退火温度升高,合金由SME SE向SE特性转变。合金的退火再结晶温度为590 ℃,在590~650 ℃退火后合金可获得50.83 %的断裂应变值,塑变性能优良,成型加工温度可选定在590~650℃之间。在使用该合金制作能耗阻尼器及相关缓冲减震装置时退火处理温度可选择大于550℃；制作超弹性器件时,退火处理温度可选择小于400 ℃和大于600 ℃。

Abstract:

Effect of annealing temperature (θa) on the transformation and the low temperature deformation characteristics in the deformed Ti-51.1Ni (Atomic fraction, %) shape memory alloy (SMA) are investigated by differential scanning calorimetry (DSC) and tensile test. The results shows that the transformation types of Ti-51.1Ni alloy change from A→R / M→R→A to A→R→M / M→R→A to A→R→M / M→A ( A-parent phase B2, R-R phase, M-martensite phase) upon cooling / heating along with increasing annealing temperature,. The R transformation temperatures (θ_R) and martensite (M) temperature hysteresis (_?θ_M) decrease, the M transformation temperature increases, and the R temperature hysteresis (_?θ_R) does not nearly change as about 6.5℃. When deformed at 10 ℃, the 400-550 ℃ annealed Ti-51.1Ni SMA shows shape memory effect (SME) + superelasticity (SE), the 600-700 ℃ annealed Ti-51.1Ni SMA shows SE, and the characteristics of alloy change from SME SE to SE. In addition, the annealing recrystallization temperature of Ti-51.1Ni SMA were 590 ℃, and the 590-650 ℃ annealed alloy could be obtained excellent capability of plastic deformation and 50.83 %Svalues of fractureSstrain, so the molding processing temperature could be selected at 590~650 ℃. When the Ti-51.1Ni alloy are used for production energy consumption ofSdamper and damping device, the suitable annealing temperature could be selected at more than 550℃, and making of superelasticSdevice, the suitable annealing temperature could be selected at 400 ℃ less and 600 ℃ more.