选区激光熔化Ti-6Al-4V合金在模拟乏燃料后处理环境中的腐蚀行为

Corrosion behavior of Ti−6Al−4V alloy fabricated by selective laser melting in simulated spent fuel reprocessing environment

研究选区激光熔化(SLM)制备的Ti-6Al-4V合金在乏燃料后处理环境中的腐蚀行为。借助光学显微镜、X射线衍射、扫描电子显微镜、电子背散射衍射以及电化学测试等手段研究SLMTi-6Al-4V合金的显微组织及耐蚀性。结果表明,相较于铸造合金,SLM Ti-6Al-4V合金在含氧化性离子的6 mol/L热硝酸溶液中的耐腐蚀性更好。进一步分析表明,SLMTi-6Al-4V合金具有α'+β的微观结构,β-Ti相含量较高且分布均匀,同时其晶粒尺寸较小、晶界密度较高,这种微观结构可提高其在含氧化性离子的硝酸中的钝化能力以及耐腐蚀性。SLM Ti-6Al-4V合金有望在乏燃料后处理过程中得到广泛应用。

The corrosion behavior of Ti−6Al−4V fabricated by selective laser melting(SLM)in simulated spent fuel reprocessing environment was investigated.The microstructure and corrosion resistance of SLM Ti−6Al−4V alloy were characterized by optical microscopy,X-ray diffraction,scanning electron microscopy,electron backscatter diffraction and electrochemical tests.It can be found that SLM Ti−6Al−4V alloy has a better corrosion resistance than the cast counterpart in 6 mol/L hot nitric acid with oxidizing ions.Further analysis indicates that SLM Ti−6Al−4V alloy exhibitsαʹ+βmicrostructure with smaller grain size and higher grain boundary density in comparison to the cast counterpart,and a higherβ-Ti phase content with uniform distribution is also observed in SLM alloy,which is conducive to enhancing its passivation ability in nitric acid with oxidizing ions,contributing to an improved corrosion resistance.It is indicated that SLM Ti−6Al−4V alloy has the potential to be used in spent fuel reprocessing process.