合金相变行为的影响
(大连理工大学 材料科学与工程学院, 大连 116024)
摘 要: 采用示差扫描量热仪（DSC）和透射电子显微镜（TEM）, 研究热/强磁场耦合时效对Ti-50.6%Ni（摩尔分数）形状记忆合金中Ti3Ni4相析出及相变行为的影响。结果表明： 经过500 ℃、 2.5 h热/强磁场耦合时效处理后, Ti-50.6%Ni合金呈现典型的三阶段相变, 即晶界附近的B2—R转变、晶内的B2—B19′转变和晶界附近的R—B19′转变； 随着磁感应强度的增加, B2—R相变峰和B2—B19′相变峰均向低温区漂移, 而R—B19′相变峰位基本保持不变。 TEM观察显示, 热/强磁场耦合时效后, 晶界附近的Ti3Ni4析出相数量明显减少, 表明热/强磁场耦合时效可能阻碍了晶粒内部的Ni向晶界周围迁移, 抑制了Ti3Ni4相的形核。
关键字: Ti-Ni形状记忆合金； 强磁场； 时效； 相变行为
（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
