摘要:
本研究对通过电子束选区熔化（SEBM）制备的TC4合金进行了表面超声滚压（USRP）处理。利用光学显微镜、X射线衍射（XRD）、电子背散射衍射（EBSD）等技术，研究了USRP对合金表面和微观结构的影响，并通过电化学测试方法分析了其腐蚀行为。结果表明，USRP在SEBM-TC4合金的表面引发了剧烈塑性变形，促使晶粒细化，形成梯度变形层（约30 μm厚），显著提高了表面光洁度和致密度。在3.5 wt.% NaCl溶液中，USRP处理样品的腐蚀电位（-0.092 VSCE）显著高于砂纸研磨样品（-0.216 VSCE），且其腐蚀电流密度降低约43.5%。此外，USRP处理后的SEBM-TC4合金表面钝化膜呈现双层结构，外层为TiO2，内层为TiO+Ti2O3。综上，USRP改善了金属的表面光洁度和致密化程度，在变形层中引入高密度位错，实现晶粒细化，并促进了致密钝化膜的形成，从而显著提高了SEBM-TC4合金的耐腐蚀性能。
Abstract:
In this study, TC4 alloy manufactured by selective electron beam melting (SEBM) was subjected to ultrasonic surface rolling processing (USRP). The effects of USRP on the surface and microstructure of the alloy were investigated using optical microscopy, X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and other techniques. The corrosion behavior was analyzed through electrochemical testing methods. The results indicate that USRP causes severe plastic deformation on the surface of SEBM-TC4 alloy, leading to grain refinement, facilitating the formation of a gradient deformation layer (~30 μm thick), and ultimately enhancing surface finish and densification. In 3.5 wt.% NaCl solution, the corrosion potential of the USRP-treated sample (-0.092 VSCE) was significantly higher than that of the sandpaper-ground sample (-0.216 VSCE), and its corrosion current density decreased by approximately 43.5%. Moreover, the passivation film on USRP-treated SEBM-TC4 exhibited a double-layer structure, with TiO2 in the outer layer and (TiO + Ti2O3) in the inner layer. In summary, USRP improves the surface finish and densification of the metal, introduces high-density dislocations in the deformation layer to refine grains, and promotes the formation of a dense passivation film, notably improving the corrosion resistance of SEBM-TC4 alloy.
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