目的 通过对NiTi合金表面进行激光熔凝处理，从而提高NiTi合金的耐腐蚀性能。方法 利用紫外激光器对NiTi合金进行表面熔凝处理，借助扫描电子显微镜(SEM)、光学显微镜(OM)、能量色散X射线光谱仪(EDX)和X射线衍射仪(XRD)等技术手段，研究了激光熔凝处理前后NiTi合金的表面显微组织、成分和相结构。测试了激光熔凝处理前后NiTi合金表面与模拟体液(SBF)的接触角、熔凝层的显微硬度等表面性能。通过全浸腐蚀试验和电化学测试，研究了熔凝层在SBF溶液中的生物腐蚀性能，并分析了腐蚀机理。结果 NiTi合金经过激光熔凝处理后，在合金的表层形成了厚度为90~150 μm的熔凝层，熔凝层主要由TiO2、β相以及少量的TiO相组成。合金表面的平均显微硬度提高了153~279HV，合金的表面接触角增大，由亲水性转为疏水性。相较于未处理的样品，熔凝处理后的样品在SBF溶液中的腐蚀电位分别正移了435 mV和413 mV，腐蚀电流密度分别下降了83%、62%左右。熔凝处理后的样品在SBF溶液浸泡168 h后，SBF溶液中的Ni²⁺浓度下降了约1/3。结论 以适当的激光加工参数对NiTi合金进行激光熔凝处理，可在NiTi合金表面形成致密的氧化膜，这层氧化膜和熔凝层可以有效地抑制NiTi合金在SBF溶液中的点腐蚀行为。

NiTi alloy with equal atomic ratio has been widely used in biomedical field because of its excellent mechanical properties and shape memory effect. However, NiTi alloy can be corroded and released harmful Ni2+ ions in human body. In this paper, laser melting was conducted on the surface of the NiTi alloy to enhance the corrosion resistance in simulated body fluid (SBF). The microstructure, phase structure of NiTi alloy modified by laser melting treatment with various process parameters, as well as the biological corrosion properties of the melted layer in SBF solution were studied. The surface physical properties of the molten layer, such as contact angle and hardness were also tested.