AZ31B镁合金表面激光熔敷 搅拌摩擦加工改性层结构与性能研究

Investigation on the Microstructure and Properties of AZ31B Magnesium Alloys Modified Layers by Laser Cladding Friction Stir Processing

摘要:

采用激光熔敷和搅拌摩擦加工技术相结合的方法对AZ31B镁合金表面分别制备了Cu Al和Si Al改性层。通过SEM、XRD、显微硬度以及电化学腐蚀测试系统对表面改性层的微观组织、相组成及耐腐蚀等性能进行分析测试。用Cu Al和Si Al粉末分别制备的改性层化合物主要由β-Al₁₂Mg₁₇及少量的AlCu₄、AlMg和Mg₂Si、AlMg及少量的β-Al₁₂Mg₁₇组成。搅拌摩擦加工改性层与镁合金基体结合良好,表面平整光滑、组织均匀细小。与镁合金基体相比,表面改性层的显微硬度和耐腐蚀性能均得到明显提高,经搅拌摩擦加工之后的添加Si Al混合粉末改性层的显微硬度值最高可达296 HV,比母材提高了385.3%；添加Cu Al混合粉末改性层的自腐蚀电位最高可达-0.975 V,比母材也提高了37.4%。

Abstract:

Al Cu and Al Si powders were prepared on the surface of AZ31B magnesium alloy by a method of combining Laser cladding and friction stir processing. The microstructure and phase analyses of the modified layer were studied by scanning electron microscopy and X-ray diffraction measurement. Meanwhile, The microhardness and corrosion resistance of the modified layer were investigated in detail. The composite modified layers with Al Cu and Al Si powders are compose of β-Al₁₂Mg₁₇, AlCu₄, AlMg and Mg₂Si, AlMg, β-Al₁₂Mg₁₇, respectively. Both modified layer showed very good bonding with the magnesium alloy substrate. The microhardness and corrosion resistance of the modified layer are higher than that of substrate. Compared with the matrix, the maximum microhardness (296 HV) of the modified layer with Al Si powders increased by 385.3%, and the maximum self-corrosion potential (-0.975 V) with Al Cu powders increased by 37.4%.