18 MeV质子辐照对TiNi形状记忆合金R相变的影响

研究了用HZ B串列加速器的18MeV质子辐照对TiNi形状记忆合金R相变的影响,辐照在奥氏体母相状态下进行。示差扫描量热法(DSC)表明,辐照后R相变开始温度TsR和逆马氏体相变结束温度TfA随辐照注量的增加而降低。当注量为1.53×1014/cm2时,TsR和TfA分别下降6K和13K,辐照未引起R相变结束温度TfR和逆马氏体相变开始温度TsA的变化。表明辐照后母相(奥氏体相)稳定。透射电镜(TEM)分析表明辐照后没有引起合金可观察的微观组织变化。辐照对R相变开始温度TsR和逆马氏体相变结束温度Af的影响可能是由于质子辐照后产生了孤立的缺陷团,形成了局部应力场,引起晶格有序度的下降所造成的。

Influence of 18 MeV proton irradiation on the R-phase transformation of a TiNi shape memory alloy

Ti 50.6at.%Ni shape memory alloy specimens were irradiated under the austenite state (parent phase) using a tandem accelerator by 18MeV protons with doses of 1.53×1013 and 1.53×1014 H+/cm2. The microstructure and phase transformation of the specimens before and after irradiation were examined by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). After the irradiation the parent phase (austenite) was stabilized. R phase transformation start temperature and the reverse martensitic transformation finish temperature decreased with the increasing proton fluence. They decreased about 13K and 6K at a dose of 1.53×1014 H+/cm2, respectively. The reverse martensitic transformation start temperature and R phase transformation finish temperature were not affected by the proton irradiation. There is no observable change in the microstructure after irradiation for the low atom displacement probability. The variation of the transformation temperature was assigned to the local stress fields and change in the ordering degree of lattice generated by proton irradiation.