铝合金表面激光熔覆铜镍合金涂层的组织、硬度与耐蚀特性研究

为提升铝合金材料的耐蚀性能，探究铝合金与合金熔覆层间的结合机理，本文利用激光熔覆技术在5083铝合金表面制备了不同Ni含量的铜镍合金熔覆层，并利用扫描电子显微镜、X射线衍射分析、硬度测试与电化学性能测试技术，分析了不同Ni含量的铜镍合金熔覆层相组成与组织形貌、铜镍合金熔覆层与铝合金基体的界面组织形貌，绘制了铝元素扩散曲线，分析了海水腐蚀过程中铜镍合金熔覆层的极化曲线。实验结果表明：所制备的铜镍合金熔覆层形貌良好无缺陷，熔覆层由网络状枝晶组成。对合金熔覆层进行XRD分析发现熔覆层主要由AlNi₃与CuNi两相组成。结合SEM、EDS分析，发现合金熔覆层的网络状枝晶为富铝相，即AlNi₃,晶间相为CuNi相。在硬度测试中，由于AlNi₃硬质相的生成，熔覆层硬度得到了提升且随着铝的向上扩散呈现一定的规律，电化学检测结果表明，铜镍合金熔覆层具有比5083铝合金更高的自腐蚀电位和较小的自腐蚀电流密度，可以有效提升5083铝合金在海水环境中的耐蚀性。

Microstructure, hardness and corrosion resistance of laser cladding copper-nickel alloy coating on aluminum alloy

In order to improve the corrosion resistance of aluminum alloy materials and explore the bonding mechanism between aluminum alloy and alloy cladding layers, copper-nickel alloy cladding layers with different Ni contents were prepared on the surface of 5083 aluminum alloy by laser cladding technology. Using scanning electron microscopy, X-ray diffraction analysis, hardness test and electrochemical performance test techniques, the phase composition and microstructure morphology of copper-nickel alloy cladding layers with different Ni contents and the interfacial microstructure morphology of copper-nickel alloy cladding layers and aluminum alloy matrix were analyzed, the aluminum diffusion curve was drawn and the polarization curve of copper-nickel alloy cladding layers during seawater corrosion was analyzed. The experimental results show that the prepared Cu-Ni alloy cladding layer has good morphology and no defects. The cladding layer is composed of network dendrites. The XRD analysis shows that the cladding layer is mainly composed of AlNi₃ and CuNi phases. Combined with SEM and EDS analysis, it is found that the network dendrites of the alloy cladding layer are AlNi₃ rich phase and CuNi phase. In the hardness test, due to the formation of AlNi₃ hard phase, the hardness of cladding layer is increased and presents a certain rule with the upward diffusion of aluminum. The electrochemical test results show that the Cu-Ni alloy cladding layer has higher self-corrosion potential and lower self-corrosion current density than 5083 aluminum alloy, which can effectively improve the corrosion resistance of 5083 aluminum alloy in seawater environment.