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采用铝热反应-自蔓延烧结法制备了钼质量分数分别为5%、10%、20%的Mo增强铜基复合材料。采用X射线衍射仪、光学显微镜、扫描电镜和透射电镜分析了复合材料的物相及微观组织形貌,并研究了钼添加量对复合材料力学性能、导电性能、热膨胀系数的影响。结果表明:该工艺制得的复合材料基体晶粒尺寸均达到纳米级,致密度均达到90%以上,硬度较纯铜提高40%以上,导电性能良好(72%IACS以上)。随着钼质量分数的增加,复合材料的硬度增加,致密度、电导率及热膨胀系数下降。当钼质量分数为20%时,复合材料的致密度为91.88%,电导率为72%IACS,硬度是纯铜的2倍,热膨胀系数较纯铜降低了13%,综合性能最佳。复合材料硬化的主要机理为强化相钼和铜基体弹性模量差别引起的模量硬化。
The Mo-reinforced Cu matrix composites with molybdenum content of 5%, 10% and 20% were prepared by aluminothermic reaction-self-propagating sintering method. The phase and microstructure of the composites were characterized by X-ray diffraction (XRD), optical microscope, scanning electron microscope and transmission electron microscope. The effects of molybdenum content on the mechanical properties, electrical conductivity and thermal expansion coefficient of the composites were also studied. The results show that the grain size of nanocomposites prepared by this process all reach nanometer level, the density reaches above 90%, the hardness is more than 40% higher than pure copper, and the conductivity is good (above 72% IACS). With the increase of the mass fraction of molybdenum, the hardness of the composites increases, and the density, conductivity and thermal expansion coefficient decrease. When the mass fraction of molybdenum is 20%, the composite has a density of 91.88%, an electrical conductivity of 72% IACS, a hardness of twice that of pure copper, and a coefficient of thermal expansion lower than that of pure copper by 13%. The main mechanism of hardening of the composite material is to strengthen the modulus hardening caused by the difference of elastic modulus between the phase molybdenum and the copper matrix.