中文摘要：

以厚度≤1 mm的Cr,Ni混合粉做中间层,在焊接温度为1650℃,真空度（3.0～4.0）×10-2 Pa,保温时间1～2 h,加压0.1 MPa条件下对钼和石墨进行扩散焊接。通过扫描电子显微镜观察焊接试样接口组织形貌,用其附带的能谱仪进行化学成分分析,用X射线衍射仪进行物相分析。并分析焊接过程中的界面反应,认为实验条件下的焊接过程与瞬间液相扩散焊（TLP）焊接机制相一致,包括中间层的熔化（或溶解）、母材溶解和迁移、等温凝固、固相成分均匀化4种相变过程,靠近母材部分界面反应遵循快速通道扩散机制,整个焊接层组元浓度梯度与薄膜源扩散模型相一致。中间层与母材元素反应形成的最终产物包括Cr3C2,Cr7C3及Mo2C等Ni以单质形式弥散其中,最终形成不同成分粒状组织,一定程度上阻止了脆性相中的裂纹扩展。石墨基体中也明显有含合金元素的新相生成,有利于实现基体与中间层的连接。

英文摘要：

With Cr,Ni mixed powder as the middle layer,welding temperature of 1650 ℃,vacuum degree of 3.0~4.0×10-2 Pa,holding time of 1~2 h under pressure of 0.1 MPa,molybdenum and graphite diffusion bonding was carried out.Specimen interface morphology was observed by using SEM,chemical composition was analyzed by EDS,and phases were determined by XRD.Through the analysis of the interface reaction during the welding process,the welding mechanism under the experimental conditions could be considered that it was consistent with the transient liquid phase bonding（TLP）.The process had four phase transition including the melting（or dissolution） of the middle layer,dissolution and migration of base metal,isothermal solidification,homogenization of solid-phase composition.The interface reaction of the part close to the base metal followed the fast-track diffusion mechanism,and the concentration gradient of the intermediate composition was the same with the film source diffusion model.The final product of interlayer reaction included Cr3C2,Cr7C3,Mo2C,Ni and so on.Ni dispersed in the interlayer.The final organization was granular.It prevented crack propagation of the brittle phase to some extent.Graphite matrix had new phase with alloying elements.It was conducive to the connection between the matrix and the interlayer.