Ti-6Al-4V表面等离子渗锆及锆合金层的性能

Plasma Surface Zirconium Alloying of Ti-6Al-4V and the Performance of the Zr-alloy

目的通过等离子表面合金化渗锆,提高Ti-6Al-4V的表面硬度及在还原性酸中的耐蚀性能。方法分别在800,850,900℃渗锆,分析研究锆合金层的成分、相组成、显微硬度及在为10%(质量分数)H2SO4溶液中的腐蚀行为,并与未处理的基材进行对比。结果 Ti-6Al-4V在三种温度下渗锆后,形成的表面合金层主要由锆在α-Ti或β-Ti中形成的固溶体组成,元素组成呈梯度分布,表面粗糙度随渗锆温度的提高而增加,硬度由表及里呈梯度下降,表面硬度比未处理的Ti-6Al-4V提高了约200HV0.1。与未处理的基材相比,Ti-6Al-4V渗锆后,在10%H2SO4溶液中的自腐蚀电位均正移,钝化电流密度均有所减小。结论 Ti-6Al-4V渗锆后,硬度和耐蚀性较基体有所提高,其中,900℃渗锆后的耐蚀性最好,800℃与850℃渗锆试样的耐蚀性次之。

Objective To improve the surface hardness and corrosion resistance of the Ti-6Al-4V in reducing acid solution by plasma surface zirconium alloying. Methods The chemical composition, phase structure and micro-hardness of the Zr-alloyed layer obtained at 800 ℃ , 850 ℃ and 900 ℃ were studied. The electrochemical behaviors of alloyed and untreated matrix in 10 % H2 SO4 solution were also studied. Results The alloyed layers formed at three different temperatures exhibited a gradient composi- tion and mainly consisted of α（ Ti, Zr）and β（ Ti, Zr）. The surface roughness of Zr-alloyed alloy increased with alloying tempera- ture. The hardness of the alloyed layer was increased by about 200HV0.1 compared with untreated Ti-6Al-4V and was gradually decreased along the alloyed depth. The corrosion potential of the alloyed layer shifted markedly to positive direction in contrast to the untreated matrix, while the passivation current density was decreased. Conclusion The micro-hardness and the corrosion resis- tance of Zr-alloyed Ti-6Al-4V were improved compared with the untreated titanium alloy. Among the temperatures tested, the cor- rosion resistance of the alloyed layer treated at 900 ℃ was the best, followed by the alloyed layer treated at 800 ℃ and 850 ℃.