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利用实验室自制的调温、调频、调载冲击实验机对3种组织成分的WC-Co硬质合金进行了不同实验条件下的冲击疲劳试验,研究了组织成分及实验条件对硬质合金冲击疲劳寿命的影响;通过扫描电子显微镜(SEM)及透射电镜(TEM)重点分析了疲劳过程中硬质合金微观组织的变化。结果表明:硬质合金的冲击疲劳寿命随试验温度和冲击能量的升高而下降,且随着冲击能量和试验温度的提高其疲劳敏感性增大。WC-Co合金的冲击疲劳断裂主要是以WC/WC界面和粘结相开裂为主,裂纹沿WC/WC和WC/Co界面及在Co相中扩展。随冲击次数的增加WC中位错数量增多并相互缠结,同时Co相发生面心立方-堆垛层错-密排六方的马氏体转变。
The impact fatigue tests of three kinds of WC-Co cemented carbide with different experimental conditions were carried out by using the laboratory-made thermostat, FM and load-impact testing machine. The impact of microstructure and experimental conditions on the cemented carbide impact Fatigue life. The microstructure of cemented carbide during fatigue was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the impact fatigue life of cemented carbide decreases with the increase of test temperature and impact energy, and its fatigue sensitivity increases with the increase of impact energy and test temperature. The impact fatigue fracture of WC-Co alloy is dominated by the cleavage of the WC / WC interface and the binder phase. Cracks propagate along the WC / WC and WC / Co interfaces and in the Co phase. The number of dislocations in WC increases with the increase of the number of impacts and entangles with each other. Meanwhile, the face-centered cubic-stacking fault-the martensitic transformation of the hexagonal hexagonal close-packed phase occurs in the Co phase.