TiNi合金相变的原位观察

In Situ Observation of Phase Transformation in TiNi Alloys

本文利用透射电镜原位观察研究ＴｉＮｉ合金中的相变。研究表明，ＴｉＮｉ合金中电子衍射谱上的漫散射条纹的出现是由于具有＜１１１＞极化的声子模软化，张应力有利于与Ｒ相及马氏体相形核有关的软模。Ｒ相变是一种可逆的热弹性位移型相变，在析出相与基体界面处形核，并通过共格界面的移动而长大，界面处的应力与成分对Ｒ相择优形核起重要作用。发现了有别于Ｒ相的二种亚稳相－Ｒ′与χ相。

Several researches of phase transformation in TiNi alloy by using Transmission Electron Microscope (TEM) have been presented briefly.It has been identified that the diffuse streak diffraction patterns of electron arise from the softening of 〈111〉 longitudinal phonon mode.The tensile stress promotes soft modes which relate to the nucleation of the R phase and the martensite phase.The R phase transformation was found to be reversible themoelastic displacive transformation,the R phase nucleates at the precipitate/matrix interface and grows by moving the coherent R/matrix interface.The stress field and composition at the precipitate/matrix interface play an important role in the formation of R phase.Two new metastable R′and χ phases have been discovered.