摘要
采用激光熔注技术在7075铝合金表面制备了Al-Cr/7075Al梯度复合涂层。采用扫描电镜(SEM)、能谱仪(EDS)和X-射线衍射(XRD)和显微硬度计等研究了复合涂层的微观结构、物相及显微硬度。结果表明:Al-Cr/7075Al梯度复合涂层与基板结合良好,无裂纹、孔隙等明显缺陷;复合涂层的表面硬度为324.2 HV0.2,是7075铝合金基体的2.28倍,涂层的硬度分布沿熔池深度方向逐渐递减,呈梯度分布;复合涂层中的增强体是由Al0.983Cr0.017、Al86Cr14、AlCr2、和Cr等混合组成,受熔池温度、熔液黏度等影响,增强体含量沿熔池深度方向逐渐减少,也呈梯度分布;Al、Cr之间的反应机理为液-固反应、固-固反应2种;复合涂层的强化机制主要是增强体承载、界面传载和位错强化。
Al-Cr/7075 Al gradient composite coating was prepared on the surface of 7075 aluminum alloy by laser melting injection technology.Microstructure,phase and microhardness of the composite coating were studied by means of scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD)and microhardness tester.The results show that the Al-Cr/7075 Al gradient composite coating has good bond with substrate,and no crack,porosity and other obvious defects are observed.The surface hardness of the composite coating is 324.2 HV0.2,which is 2.28 times that of the 7075 aluminum alloy substrate.The hardness of the coating gradually decreases along the depth of molten pool,showing gradient distribution.The reinforcement in the composite coating is composed of Al0.983Cr0.017,Al86Cr14,AlCr2 and Cr,which is affected by the temperature of molten pool and viscosity of molten liquid,and the reinforcement content gradually decreases along the depth of the molten pool,also showing a gradient distribution.The reaction mechanism between Al and Cr is liquid-solid reaction and solid-solid reaction.The strengthening mechanism of the composite coating is mainly reinforcement bearing load,interface transferring load and dislocation strengthening.
作者
王秋林
朱金波
李昂
门正兴
赵龙志
WANG Qiu-lin;ZHU Jin-bo;LI Ang;MEN Zheng-xing;ZHAO Long-zhi(Chengdu Aeronautic Polytechnic,Chengdu 610100,China;Avic Chengfei Commercial Aircraft Co Ltd,Chengdu 610092,China;School of Materials Science and Engineering,East China Jiao Tong University,Nanchang 330013,China)
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2020年第3期138-144,共7页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金(51761012)
四川省教育厅资助项目(18ZB0058)
成都航空职业技术学院重点科研项目(061623Y,061902)。
关键词
激光熔注
梯度复合涂层
微观结构
反应机理
显微硬度
laser melting injection technology
gradient composite coating
microstructure
reaction mechanism
microhardness
