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对单晶高温合金DD6进行表面渗碳处理,采用SEM、TEM研究了DD6合金渗碳层组织,运用EDS与SAD分析了渗碳层内碳化物的类型。结果表明,表面渗碳处理后,在渗碳层γ相内析出大量细小的MC型碳化物,与合金名义成分相比,其化学成分富含铌、钽和钼,而铝和镍含量较低。该碳化物呈块状析出,尺寸约为0.1μm,弥散分布在渗碳层区域内。由于碳化物的析出,渗碳层区域内的γ′相不能保持完整的立方化形态。渗碳处理温度越高,渗碳层深度越大。MC碳化物与基体γ相之间存在[001]MC∥[001]γ,(200)MC∥(200)γ的晶体学取向关系。
The surface carburization of single crystal superalloy DD6 was studied. The microstructure of carburized layer of DD6 alloy was studied by SEM and TEM. The types of carbides in carburized layer were analyzed by EDS and SAD. The results show that after the surface carburizing treatment, a large number of small MC carbides are precipitated in the γ phase of the carburized layer. Compared with the nominal composition of the alloy, the chemical composition is rich in niobium, tantalum and molybdenum while the aluminum and nickel contents are lower . The carbide precipitated in the form of a size of about 0.1μm, dispersedly distributed in the carburized layer region. Due to the precipitation of carbides, the γ ’phase in the carburized layer region can not maintain a complete cubic morphology. Carburizing temperature is higher, the greater the depth of carburized layer. The crystallographic orientations of [001] MC∥ [001] γ and (200) MC∥ (200) γ exist between the MC carbides and the matrix γ phase.