YG8硬质合金渗硼层组织和性能的分析

ANALYSIS ON MICROSTRUCTURE AND PROPERTYOF BORONIZED LAYER OF YGS HARD ALLOY

用Ｘ射线衍射、电子探针、透射电镜和光学金相方法，研究了钨钴类硬质合金渗硼层的硬化机理。结果表明：ａ）钨钴类硬质合金渗硼导致显微组织发生变化，碳化钨颗粒的间距增大，棱角变圆，相对量减少。ｂ）ＹＧ８渗硼层中发现了钴的硼化物和钨的硼化物，前者的硬度为１４００～２０００ＨＶ；后者的硬度为２０００～３１００ＨＶ．ｃ）电子探针分析表明：渗硼过程中在硼的扩散层内元素重新分布，钴向内迁移，钨和碳向外扩散．ｄ）ＹＧ８硬质合金渗硼层硬度为２７００ＨＶ以上，耐磨性明显提高。渗硼工艺可用于硬质合金高速拉拔模具。

By the way of Xr-ay diffraction. EPW and metallographic examination, thesurfaee hardenins mechanism of boronized cobalt-tungsten hard alloy is studied. It is shownthat: a) boronizing changes microstructure of the hard alloy, it reduces the voluiTie fractionof tunssten earbide, the distance between these carbide particles is incrcased, theircrystallographic morphology becomes spheroidizedi b) cobalt and tunssten borides are foundin the boromzed layer, the former liardness is 1400～2000HV, the latter one is 2000～3100HV; c) EPMA indieates, during boronizing, elements are redistributed in the boronizeddiffusion layer, eabalt moves inward, tungsten and carbon outward; d) hardness ofboronized layer of YG8 alloy is about 2700～3100HV. Therefore, the wear-resistance ofthe alloy boronized is significantiy iinproved. Hence, the boronizins techilology can be usedfor liard alloy to make high-speed puiling die.