通过分析合金表面形貌以及表面物相,研究了新型Ti(C,N)/AlCoCrFeNi金属陶瓷烧结过程中粘结相的表面富集行为.结果表明,在1 300 ℃下烧结60 min后,合金烧结体表面发生了明显的富集,并形成了第三相,即类似M6C结构的缺碳相(η).该现象的产生主要归因于烧结过程中,表面脱碳形成了表面和内部的碳浓度差、固溶体浓度差以及温度差,促使金属元素钨、钽、钛、钼以扩散的方式向内迁移,表面的低碳造成合金的共晶温度提高,表面的液相量减少从而产生负压张力,导致内部的液相向表面迁移.另外,由于合金微观组织中体积含量不同的粘结相区域产生压力差,导致在烧结过程中富钨区的粘结相倾向于向液相量低的贫钨区迁移,使得金属粘结相逐渐向表面迁移、渗透,富集于表面.%Through the analysis of surface topography and phase composition of the alloy,the concentrating behavior of binder on the surface of Ti(C,N)/AlCoCrFeNi cermets during sintering process were studied.The results indicated that the binder was obviously concentrated on surface when sintered under 1 300 ℃ for 60 minutes,and formed a third phase containing M6C-type brittle phase(η).This phenomenon could attribute to the carbon concentration difference,solid solution concentration difference and temperature difference of the surface and interior,which caused by decarbonization during sintering.It urged the migration of W,Ta,Ti,Mo to the interior in a diffusion way.Besides,the surface decarbonization also caused the increase of alloy eutectic temperature.Thus,the reduction of surface liquid phase leaded to the generation of negative pressure,which made the inner liquid phase transfer to the surface.In addition,binding phase regions with different volume content in the microstructure might lead to the pressure difference,and the rich W region was apt to migrate to the poor W region with low liquid phase during sintering,which caused the binding phase transfer,permeate and finally gathered on the surface.
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