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| Al-Cr composite coating laser cladding on 7075 aluminum alloy |
| ZENG Xiaoping1，WANG Qiulin1，MA Yaxin1，2，ZHANG Hong3 |
| （1. Chengdu Aeronautic Polytechnic, Chengdu 610100, China; 2. Beijing Iron and Steel Research Institute, Bei‐
jing 100081, China; 3. Failure Mechanics and Engineering Disaster Prevention and Mitigation Key Laboratory of
Sichuan Province, College of Architecture and Environment, Sichuan University, Chengdu 610065, China） |
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Abstract In order to strengthen the surface of 7075 aluminum alloy, an Al-Cr composite coating was prepared
by laser cladding technology. Scanning electron microscope (SEM) and optical metallurgical microscope (OM)
were used to observe the structure of the composite coating. Energy dispersive spectrometer (EDS) was used to
elemental analysis, X-ray diffraction (XRD) was used to phase analysis, and the micro-hardness of the composite
coating was tested. The results show that the Al-Cr composite coating prepared by laser cladding technology is
relatively smooth, without obvious cracks, and forms a good metallurgical bond with the substrate. The compos‐
ite coating consists of a metal phase (Al and a small amount of Cr) and a ceramic phase (AlxCry intermetallic
compounds). There are two reactions mechanisms of Cr and Al in the coating: liquid-solid reaction and solid-sol‐
id reaction. The Al phase of the metal plays the roles to bond the coating to the substrate，increase the toughness
of the coating and reduce the generation of cracks. The coating experiences different laser passes, so there are dif‐
ferences in the structure and phase composition of each part, which leads to changes in performance. The microhardness of the coating is gradually distributed along the depth of the molten pool and gradually decreases. The surface hardness is maximum 977.4HV
0.5, which is a 6.88 times increase compared to 7075 in the T6 state.
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Received: 10 July 2021
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Corresponding Authors:
张 宏（1982—），男，博士，副教授，主要研究方向为新型材料的力学问题与表面处理。
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2022, Vol. 32 
