In situ evaluation of the transformation behaviour of NiTi-based high temperature shape memory alloys
In situ evaluation of the transformation behaviour of NiTi-based high temperature shape memory alloys
复制标题
DOI：
10.1016/j.intermet.2013.11.009
复制
发表时间：
2014-03-01
期刊：
影响因子：
4.4
通讯作者：
Dye, D.
中科院分区：
文献类型：
--
作者：
Azeem, M. A.;Dye, D.
使用原位同步加速器 X 射线衍射研究了通过铸锭冶金法制造的含有 15 at.% Hf 和 Zr 以及 0 at.% 或 3 at.% Cu 的细晶粒多晶 NiTi 形状记忆合金，以检验生产稳定且经济实惠的高温形状记忆合金的可行性。生产的合金具有高热滞后，超过 70 摄氏度，但 Ni50Ti35Hf15 的温度超过 250 摄氏度。添加 3 at.% Cu 并没有显着降低每次循环的转变温度下降，但确实降低了转变温度。观察了前五个热循环期间晶格参数的演变。在所有检查的合金中，b(B19')晶胞方向均发现负热膨胀，并且发现转变区域的晶格参数存在显着偏差。观察到终点 B19' 晶格参数的每周期演化，但 B2 相没有发现这种演化，这是通过界面位错数量的增加来合理化的。 (C) 2013 Elsevier Ltd. 保留所有权利。
Fine grained polycrystalline NiTi shape memory alloys containing 15 at.% Hf and Zr and zero or 3 at.% Cu fabricated by ingot metallurgy were investigated using in situ synchrotron X-ray diffraction in order to examine the viability of producing stable and affordable high temperature shape memory alloys. The alloys produced had a high thermal hysteresis, in excess of 70 degrees C but At temperatures of over 250 degrees C were obtained for Ni50Ti35Hf15. 3 at.% Cu additions did not significantly reduce the per-cycle degradation of transformation temperatures but did reduce the transformation temperatures. The evolution of the lattice parameters during the first five thermal cycles was observed. Negative thermal expansion was found in the b(B19'), cell direction in all the alloys examined and significant deviations in the lattice parameters in the region of transformation were found. A per-cycle evolution in the end-point B19' lattice parameters was observed, but no such evolution was found for the B2 phase, which is rationalised by appealing to the increase in population of interface dislocations. (C) 2013 Elsevier Ltd. All rights reserved.