Co/Ni比对93W-Co-Ni钨合金烧结温度及力学性能的影响

Influence of Co/Ni Ratio on Sintering Temperature and Mechanical Properties of 93W-Co-Ni Tungsten Heavy Alloy

以Co、Ni作黏结剂，选择不同Co/Ni比，用粉末冶金法制备出HRC硬度在30～43之间的93W-Co-Ni钨合金。采用光学金相、扫描电镜对合金组织形貌进行表征，采用准静态拉伸试验对合金的抗拉强度及延伸率进行测试，采用洛氏硬度计对合金硬度进行测定。结果表明：随着Co/Ni比增加，合金的烧结温度逐渐增加，其抗拉强度与延伸率急剧降低，而硬度先增加之后趋于稳定；当Co/Ni≥1.0时，合金抗拉强度很低，延伸率≤1%；当Co/Ni≥4时，其HRC硬度值稳定在41～43之间，明显高于一般的W-Ni-Fe合金，这主要与Co对W基体的润湿性较差及两者之间易形成脆性化合物Co7W6有关。

93W-Co-Ni tungsten heavy alloys with HRC hardness of 30-43 were prepared by means of powder metallurgy with different Co/Ni ratio as binding admixture. Optical microscope （OM）,scanning electricity microscope （SEM）were used to characterize microstructure of alloys, respectively. The tensile strength and elongation of alloys were tested with quasi-static tensile testing machine, and the hardness was tested by a Rockwell hardness tester. The results indicate that with increasing Co/Ni ratio the sintering temperature gradually raises, the tensile strength and elongation rapidly decrease, respectively. Meanwhile, the hardness first increases and then becomes stable. When the Co/Ni ratio exceeds 1.0 the tensile strength is lower, the elongation is less than or equal to 1%. As the Co/Ni ratio exceeds 4.0 the hardness range is from 41 to 43,which is significantly higher than that of general W-Ni-Fe alloy. The mechanical properties of 93W-Co-Ni tungsten heavy alloy are found mainly dependent on the lack of soakage property of the Co to W base and formation of intermetallic phase Co 7W6.