碳含量对WC-TiC-Co合金组织与性能的影响

Effects of carbon content on the microstructure and performance of WC-TiC-Co cemented carbides

先将由W、Co、C和TiC组成的混合粉末碳化,得到以η相为主相的粉末,补充碳黑后进行第二步碳化制备不同碳含量的WC-TiC-Co复合粉末,随后真空烧结成块体合金材料,研究碳含量w(C)对合金物相组成、WC晶粒尺寸与(Ti,W)C固溶体形貌以及合金力学性能的影响。结果表明,w(C)对WC-TiC-Co合金的物相组成和晶粒尺寸具有显著影响。缺碳时,合金中残留不规则形状的η相,并与WC相形成充分冶金结合,Co相分布在WC和(Ti,W)C相的界面处;适度富碳时,WC晶粒形状相对规则,WC和(Ti,W)C相尺寸增大,(Ti,W)C相与黏结相中的W含量增加。具有合适w(C)的WC-TiC-Co合金,硬度(HRA)为91.7,横向断裂强度为1678 MPa,断裂韧性为10.2 MPa·m1/2。

The powders with main phase ofηphase were synthesized via the carbonization of W,Co,C and TiC mixtures firstly,WC-TiC-Co composite powders with different carbon contents were then synthesized by the carbonization of theηphase powder.WC-TiC-Co cemented carbides were prepared by vacuum sintering.The effects of carbon contents on the phase consistent,grain size,morphology and mechanical performance were investigated.The results show that the carbon content is the key factor affecting the phase composition and grain size of the alloy.Theηphase with irregular shape remains in carbon-poor alloys and forms a metallurgical bonding with WC phase.Co phase tends to distribute at the interface between WC and(Ti,W)C phases.WC grains in carbon-rich alloys show a more regular shape than that in carbon-poor alloys.The size of WC and(Ti,W)C phase increase and the W content in(Ti,W)C phase and binder phase also increases.The alloy with suitable carbon amount has the hardness(HRA)of 91.7,the transverse rupture strength of 1678 MPa and the fracture toughness of 10.2 MPa·m1/2.