AZ91镁合金表面激光熔覆Al-Cu合金涂层的组织与性能

发布时间：2019-01-18 18:46

【摘要】：利用激光熔覆技术在AZ91镁合金表面制备Al-30%Cu(质量分数)合金涂层。采用X射线衍射仪、扫描电子显微镜、显微硬度仪、电化学工作站表征分析激光熔覆试样的组织和性能。结果表明:激光熔覆层与基体呈现出良好的冶金结合,无明显的气孔裂纹等缺陷。其中,熔覆区出现大量的牙齿状、花瓣状和细颗粒状组织,结合区为典型的树枝晶组织。XRD结果表明:熔覆层主要由二元相Mg_(17)Al_(12)、AlMg、CuMg_2和三元相Al_2CuMg、Mg_(32)Al_(47)Cu_7组成。由于晶粒细化和新形成的金属间化合物的共同作用,合金熔覆层的显微硬度平均值(392.2HV)为AZ91镁合金基体硬度(约70HV)的5.6倍。熔覆层的腐蚀电位比基体的提高179.2 mV,腐蚀电流密度较基体的降低两个数量级,耐蚀性得到较大的改善。
[Abstract]:Al-30%Cu (mass fraction) alloy coatings were prepared on AZ91 magnesium alloy by laser cladding. The microstructure and properties of laser cladding samples were characterized by X-ray diffractometer, scanning electron microscope, microhardness analyzer and electrochemical workstation. The results show that the laser cladding coating has a good metallurgical bonding with the substrate, and there are no obvious defects such as pore cracks. Among them, a large number of dentate, petal-like and fine granular structures appeared in the cladding zone, and the binding zone was a typical dendritic structure. The XRD results showed that the cladding layer was mainly composed of binary phase Mg_ (17) Al_ (12), AlMg,). CuMg_2 and ternary phase Al_2CuMg,Mg_ (32) Al_ (47) Cu_7. Due to the interaction of grain refinement and newly formed intermetallic compounds, the average microhardness (392.2HV) of the cladding layer is 5.6 times higher than that of AZ91 magnesium alloy substrate (about 70HV). The corrosion potential of the cladding layer is increased by 179.2 mV, and the corrosion current density of the cladding layer is decreased by two orders of magnitude compared with that of the substrate, and the corrosion resistance is greatly improved.
【作者单位】：南华大学机械工程学院;
【基金】：国家自然科学基金资助项目(51201088) 湖南省自然科学基金资助项目(2015JJ3109) 南华大学青年英才支持计划项目(2014-002) 湖南省重点学科建设项目(湘教发[2011]76号)~~
【分类号】：TG174.44

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