Effects of cubic carbides and La additions on WC grain morphology,hardness and toughness of WC-Co alloys

Effects of Cr3C2,VC and La2O3 additions on the WC grain morphology,hardness and toughness of WC-10Co alloys were investigated.To intensify the grain growth driving force,nano W and nano C,instead of the conventionally used WC,were used as the starting materials.To obtain a three-dimensional WC grain morphology,the natural sinter skins of the alloys were observed directly by scanning electron microscopy.It is shown that the additions have a strong ability in regulating the WC grain morphological and grain size distribution characteristics and the combinations of hardness and toughness.Due to the formation of regular and homogeneous triangular platelet WC grains,WC-10Co-0.6Cr3C2-0.06La2O3 alloy shows an excellent combination of hardness and toughness.The morphological regulation mechanism,the relationship between the WC grain morphology and the properties were discussed.

选择性电溶法再生WC原料中杂质Ti在硬质合金烧结过程中的作用行为

采用基于选择性电溶法的再生超细WC粉末为原料,制备WC-10Co和WC-10Co-0.06La_2O_3硬质合金,研究原料中的杂质Ti,Ta和V在烧结过程中的作用行为。结果表明,杂质Ti,Ta和V同步迁移至合金烧结体表面,形成WTi(Ta,V)C_2富集相;合金中微量稀土La可促进Ti的表面迁移。Ti如果不是以固溶体型稳定化合物的形式添加,容易导致硬质合金中出现Co3W3C脱碳相和板状WC晶粒的形成。硬质合金微观组织结构的均匀性与Ti在合金中分布的均匀性密切相关。