电子辐照影响TiNi形状记忆合金R相变的研究

Effect of electron irradiation on the R-phase transformation of TiNi shape memory alloy

用能量为 1.7MeV不同注量的电子辐照了TiNi形状记忆合金 ,通过温度控制使辐照在合金的R相状态进行 ,发现辐照使合金的奥氏体逆转变开始温度As 和结束温度Af 升高 ,随着辐照注量的增加有增大的趋势 ,且奥氏体转变滞后也有所增大 ;R相转变开始点Rs 和转变结束点Rf 略有增加。XRD结果表明电子辐照造成了R相点阵畸变 ,随辐照注量的增加有增大的趋势。这一变化被认为是辐照引入的点缺陷导致了R相稳定化 ,并且部分缺陷钉扎了R相界面造成的。

Specimens of NiTi shape memory alloy were irradiated with an energy of 1.7 MeV electron over different time. The electric resistance of the specimens was measured under similar conditions before and after electron irradiation at 293-363 K. The transformation temperature As of nitinol alloy is increased from 321 K for the virgin sample to 325.5 K and Af from 336 K to 342 K when the dose is 1.58×1020/m2, and they shift to 328 K and 346 K respectively when the dose is increased to 1.58×1021/m2. The hysteresis of R-phase transformation and R-phase inverse transformation are increased from 9.5 K to 11.5 K and from 15 K to 18 K respectively. But the Rs and Rf are only varied about 1-2 K. The results of XRD show that the point-defect makes the lattice distortion of R-phase induced by electron irradiation. This is an indication that increasing the electron fluency enhances the creation of defects and the production of lattice disorder by electron irradiation.