合金相變行為的影響
(大連理工大學(xué) 材料科學(xué)與工程學(xué)院, 大連 116024)
摘 要: 采用示差掃描量熱儀（DSC）和透射電子顯微鏡（TEM）, 研究熱/強(qiáng)磁場(chǎng)耦合時(shí)效對(duì)Ti-50.6%Ni（摩爾分?jǐn)?shù)）形狀記憶合金中Ti3Ni4相析出及相變行為的影響。結(jié)果表明： 經(jīng)過(guò)500 ℃、 2.5 h熱/強(qiáng)磁場(chǎng)耦合時(shí)效處理后, Ti-50.6%Ni合金呈現(xiàn)典型的三階段相變, 即晶界附近的B2—R轉(zhuǎn)變、晶內(nèi)的B2—B19′轉(zhuǎn)變和晶界附近的R—B19′轉(zhuǎn)變； 隨著磁感應(yīng)強(qiáng)度的增加, B2—R相變峰和B2—B19′相變峰均向低溫區(qū)漂移, 而R—B19′相變峰位基本保持不變。 TEM觀察顯示, 熱/強(qiáng)磁場(chǎng)耦合時(shí)效后, 晶界附近的Ti3Ni4析出相數(shù)量明顯減少, 表明熱/強(qiáng)磁場(chǎng)耦合時(shí)效可能阻礙了晶粒內(nèi)部的Ni向晶界周?chē)w移, 抑制了Ti3Ni4相的形核。
關(guān)鍵字: Ti-Ni形狀記憶合金； 強(qiáng)磁場(chǎng)； 時(shí)效； 相變行為
（School of Materials Science and Engineering,
Dalian University of Technology, Dalian 116024, China）
Abstract: The effects of thermo-high magnetic field coupled aging treatment on the precipitation of Ti3Ni4 and phase transformation behavior of Ti-50.6%Ni(mole fraction) shape memory alloy were investigated by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The results show that a typical three-step martensitic transformation occurs during the cooling and heating cycles after thermo-high magnetic field aging treatment under all three magnetic intensities. Clear shifts to lower temperatures after aging are observed in the peak position of the B2—R phase and the peak position of the B2—B19′ phase with increasing magnetic intensity varied from 0 to 10 T. However, the number of Ti3Ni4 precipitations reduces with increasing magnetic intensity. It is suggested that the thermo-high magnetic field coupled aging treatments may suppress the movement of Ni atoms from interior region of the grain to grain boundary as well as the nucleation of Ti3Ni4 precipitations around the grain boundary.
Key words: Ti-Ni shape memory alloy; high magnetic field; aging treatment; phase transformation behavior
