粉末冶金法制备Ta–W–Si合金

Preparation of Ta-W-Si alloy by powder metallurgy method

采用热压烧结和放电等离子烧结的方法制备了Ta–W–Si合金,利用X射线衍射分析、扫描电子显微镜观察、背散射电子成像及能谱分析等手段研究了合金的显微结构和相组成,并讨论了烧结方式和硅质量分数对合金烧结致密化和硬度的影响。结果表明,两种烧结方式烧结后的样品相对密度均达到了96%以上,可以实现致密化,硅元素的添加有利于合金的致密化;扫描电子显微观察和背散射电子成像显示合金中出现两种不同区域,物相分析存在Ta–W与Ta3Si两相;硅元素的添加有利于提高合金硬度,硅化物第二相强化、细晶强化和晶界区的氧化富集是强化的主要机制。

The Ta–W–Si alloys were prepared by hot pressed sintering and spark plasma sintering.The microstructure and phase composition of sintered alloy were investigated by XRD（X-ray diffraction）,SEM（scanning electron microscopy）,BSE（backscattered electron imagine）,and EDS（energy dispersive spectrum）,and the influences of sintering method and silicon content by mass on densification and hardness were analyzed.The results show that,the relative density of alloy prepared by two sintering methods reaches over 96%,and the addition of silicon element is benefited to the densification of alloy.Two different regions can be found in SEM and BSE images,which are identified as Ta–W and Ta3Si by XRD pattern.Hardness increases clearly with the addition of silicon element.The primary strengthening mechanisms are the second-phase strengthening of silicides,the grain refinement strengthening,and the oxidative concentration in grain boundary region.