Evolution of microstructure and high temperature hardness in WCxTaC-Co cemented carbides
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摘要: 通过扫描电镜(SEM)、X射线衍射(XRD)、电子探针微区分析(EPMA)、常规物理力学性能检测以及高温硬度测试方法,研究WC-Co硬质合金中添加质量分数为0.00%~3.00%的TaC对其组织结构、力学性能以及高温硬度的影响。研究结果表明:当TaC质量分数低于0.50%时,TaC主要溶解于硬质合金黏结相中,起固溶强化和抑制晶粒长大的作用,合金的室温维氏硬度和抗弯强度明显提升;当TaC质量分数由0.50%增加至3.00%时,合金结构中开始出现不均匀分布的(Ta,W)C析出相,合金的室温维氏硬度缓慢增加,抗弯强度先缓慢增加而后下降。添加TaC有助于提升硬质合金的高温硬度,提升效果与TaC添加量存在一定的正相关关系。在1000℃高温下,未添加TaC的合金高温维氏硬度为802 MPa,而添加质量分数1.50%的TaC的合金高温维氏硬度明显改善,其高温硬度值可达1 025 MPa。Abstract: Influence of TaC addition with 0.00% to 3.00% (mass fraction) on the microstructure, mechanical performance and high temperature hardness was investigated through SEM, XRD, EPMA analysis and mechanical tests including high temperature hardness measurement. The results show that when the mass fraction of TaC is less than 0.50%, TaC is mainly dissolved in the bond phase, strengthening the solid solution and inhibiting the grain growth, and the Vickers hardness and the bending strength of the alloy at room temperature are obviously improved. When the mass fraction of TaC increases from 0.50% to 3.00%, the unevenly distributed (Ta, W) C precipitated phase begins to appear in the structure, and the Vickers hardness of the alloy at room temperature increased slowly, while the bending strength increased slowly and then decreased. The addition of TaC helped to enhance the hardness of cemented carbide at high temperature, and the effect of improvement was positively related to the amount of TaC added. At 1000℃, the high temperature hardness of the alloy without TaC was only 802 MPa, while the alloy with a mass fraction of 1.50% TaC improved the hardness of the alloy at high temperature, and its high temperature hardness could reach 1 025 MPa.
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Key words:
- cemented carbide /
- TaC /
- grain growth inhibitor /
- high temperature hardness
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