School of Materials Science and Engineering, Beihang University, Beijing 100191, China.
J Mech Behav Biomed Mater. 2012 Sep;13:174-84. doi: 10.1016/j.jmbbm.2012.04.004. Epub 2012 Apr 25.
NiTi shape memory alloy was modified by Hf ion implantation to improve its wear resistance and surface integrity against deformation. The Auger electron spectroscopy and x-ray photoelectron spectroscopy results indicated that the oxide thickness of NiTi alloy was increased by the formation of TiO₂/HfO₂ nanofilm on the surface. The nano-hardness measured by nano-indentation was decreased even at the depth larger than the maximum reach of the implanted Hf ion. The lower coefficient of friction with much longer fretting time indicated the remarkable improvement of wear resistance of Hf implanted NiTi, especially for the sample with a moderate incident dose. The formation of TiO₂/HfO₂ nanofilm with larger thickness and decrease of the nano-hardness played important roles in the improvement of wear resistance. Moreover, Hf implanted NiTi exhibited larger pseudoelastic recovery strain and retained better surface integrity even after being strained to 10% as demonstrated by in situ scanning electron microscope observation.
铪离子注入改性镍钛形状记忆合金以提高其耐磨性和抗变形表面完整性。俄歇电子能谱和 X 射线光电子能谱结果表明，表面形成了 TiO₂/HfO₂纳米薄膜，增加了镍钛合金的氧化层厚度。纳米压痕测量的纳米硬度即使在注入铪离子的最大深度以上的深度也降低了。具有更长微动时间的较低摩擦系数表明，铪注入的镍钛的耐磨性得到了显著提高，特别是对于中等入射剂量的样品。TiO₂/HfO₂纳米薄膜厚度的增加和纳米硬度的降低在提高耐磨性方面发挥了重要作用。此外，原位扫描电子显微镜观察表明，即使在应变至 10%时，铪注入的镍钛也表现出较大的伪弹性回复应变，并保持较好的表面完整性。
