烧结气氛对Mo_2FeB_2基金属陶瓷显微组织和力学性能的影响

Effect of Sintering Atmosphere on Microstructure and Mechanical Properties of Mo_2FeB_2-based Cermets

本文运用XRD和SEM等对比研究了烧结气氛对Mo2FeB2基金属陶瓷相组成、显微组织和力学性能的影响。结果表明,当烧结温度为1250℃,保温时间为40min时,真空烧结后,金属陶瓷可获得较均匀的显微组织和较佳的力学性能,抗弯强度为1774MPa,硬度为90.4HRA;氩气气氛烧结时,由于碳不能完全除去粉末颗粒表面和B2O3中的氧,降低了烧结过程中液相对硬质相颗粒的润湿性,从而导致金属陶瓷的力学性能明显降低;氮气气氛烧结时,粘结相Fe与氮气发生反应生成了Fe3N,导致烧结过程中没有出现液相,未能得到致密的烧结体。

The phase composition,microstructure and mechanical properties of Mo2FeB2-based cermet under different sintering atmospheres were investigated by means of X-ray diffraction（XRD） and scanning electron microscopy（SEM）.The results show that,when the cermet is sintered at 1 250 ℃ for 40 minutes,homogeneous microstructure and superior mechanical properties are obtained by vacuum sintering,the TRS is 1 774 MPa and the hardness is 90.4 HRA.As for the cermet sintered in argon,the oxygen in B2O3 and on the surface of the grains can not be reduced by carbon,the residual oxygen reduces the wetting property of the liquid metal to the hard grains during sintering,which results in the mechanical properties of the cermet obviously decrease.Fe3N is formed by the reaction of nitrogen and Fe binder,so no liquid phase appears during sintering and dense sintered body is not obtained.