【摘 要】
：
Polycrystalline cubic boron nitride (PcBN) compacts,using the mixture of submicron cubic boron nitride (cBN) powder and hexagonal BN (hBN) powder as starting ma
【机 构】
：
Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China“,”College of Me
论文部分内容阅读
Polycrystalline cubic boron nitride (PcBN) compacts,using the mixture of submicron cubic boron nitride (cBN) powder and hexagonal BN (hBN) powder as starting materials,were sintered at pressures of 6.5-10.0 GPa and temperature of 1750 ℃ without additives.In this paper,the sintering behavior and mechanical properties of samples were investigated.The XRD pattes of samples reveal that single cubic phase was observed when the sintering pressure exceeded 7.5 GPa and hBN contents ranged from 20 vol.％ to 24 vol.％,which is ascribed to like-inteal pressure generated at grain-to-grain contact under high pressure.Transmission electron microscopy (TEM) analysis shows that after high pressure and high temperature (HPHT) treatments,the submicron cBN grains abounded with high-density nanotwins and stacking faults,and this contributed to the outstanding mechanical properties of PcBN.The pure bulk PcBN that was obtained at 7.7 GPa/1750 ℃possessed the outstanding properties,including a high Vickers hardness (～ 61.5 GPa),thermal stability (～ 1290 ℃ in air),and high density (～ 3.46 g/cm3).
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