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本文采用同时测量内耗、模量及电阻的方法,对NiTi合金变温过程中所发生的正、反马氏体相变及可逆I/C相变进行了系统的研究。结果表明,变温马氏体相变及I/C相变过程中内耗均为粘弹性型内耗,是相界面在克服粘滞性阻力而运动时引起的。从界面动力学出发,研究了相变过程中界面的运动动力学行为。由实验数据求得了马氏体相变过程中界面动力学关系的具体表达式为:V=V~*exp(—△G~*/△G—△G_R);相变过程内耗表达式为: Q~(-1)=(n~2)/2·(μ△G~*)/((△G—△G_R)~2)·(dF)/(dT)·T/ω;相变阻力△G_R约为10cal/mol的数量级。讨论了相变过程中的“软模”效应。马氏体相变过程中的模量“软化”来自声子模的软化和界面运动引起的附加模量亏损两个方面。
In this paper, the simultaneous measurement of internal friction, modulus and resistance was used to systematically study the positive and anti-martensitic transformations and the reversible I / C transitions during the temperature transformation of NiTi alloys. The results show that the internal friction in variable temperature martensitic transformation and I / C phase transformation is viscoelastic internal friction, which is caused by the phase interface when it overcomes the viscous resistance. Starting from the interface dynamics, the kinematic behavior of the interface during the phase transition was studied. The specific expression of interface dynamics in martensitic transformation is obtained from the experimental data as follows: V = V * exp (- △ G ~ * / △ G- △ G_R) Q -1 -1 / 2 · (μΔG ~ *) / (ΔG- ΔG_R) ~ 2) · (dF) / (dT) · T / ω; phase change resistance △ G_R is on the order of 10 cal / mol. The “soft mode” effect during phase transition is discussed. Modulus “softening” during martensitic transformation comes from softening of phonon modes and loss of additional modulus due to interface movement.