单晶高温合金真空钎涂MCrAlY-Cr3C2涂层的研究
Research on vacuum brazing MCrAlY-Cr3C2 coating on single crystal superalloy
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摘要: 为了提高单晶高温合金的高温耐磨抗氧化涂层,采用真空钎涂工艺制备了MCrAlY-Cr3C2复合涂层,并采用OM,SEM,XRD,EDS,EPMA和显微硬度试验等手段对涂层的组织、成分和硬度进行分析。结果表明,涂层主要由γ+γ’,Cr7C3,Cr23C6,Ni3Si和Cr3Si组成,由于界面互扩散,界面上生成了含Mo,W的硅化物,且单晶基体的二次反应区中析出了各种形态的富Ta,Ti的碳化物。涂层中由于添加了碳化物强化相,显微硬度比单晶基体提高了近3倍,但分布不均匀;涂层与基体界面处由于固溶强化效果减弱,析出的硬脆相对硬度影响不大,因此硬度提升不够明显。Abstract: MCrAlY-Cr3C2 composite coatings were prepared by using vacuum brazing coating process to improve the high temperature wear resistance and oxidation resistance of single crystal superalloy. Methods of OM, SEM, XRD, EDS, EPMA were employed to investigate the microstructures and compositions of the coatings. Results shows that, the coating consists of γ+γ’, Cr7C3, Cr23C6, Ni3Si and Cr3Si phases. Due to the interfacial interdiffusion, some silicides containing Mo and W are precipitated on the interface, while carbides riched in Ta and Ti with various morphologies are precipitated in the secondary reaction zone of the single crystal superalloy base metal. The hardness of the coating is obviously improved about 3 times, while the distribution is not uniform. The hardness on the interface between coating and substrate is low and the strengthening effect is not obvious because the solid solution strengthening effect is weak, which leads to the hard and the brittle phases have few effects on hardness.