(1. 中南大学 粉末冶金国家重点实验室，长沙 410083；
2. 中南大学 粉末冶金研究院，长沙 410083)
摘 要: 采用等离子旋转电极(PREP)法制备高温合金粉末，通过热等静压(HIP)和热挤压(HE)进行固结成型，对制备的粉末及HIP、HE态合金内部和表面显微组织进行表征，探索镍基高温合金原始颗粒边界(PPB)的组成、形成机制及组织演化特征。结果表明：合金在粉末态已发生元素偏析，粉末表层有细小的富Al氧化物颗粒，且颗粒表面有Zr、C、O元素的富集层；合金PPB主要为连续的大尺寸 相、MC型碳化物、Al2O3和富Zr的氧化物颗粒；PPB形成机制是在温度场的作用下，碳化物、 相和氧化物易于在结合面析出，合金经热挤压后，原始颗粒边界上大的 相完全消失，连续的PPB被破碎，形成含MC碳化物和少量氧化物的沿挤压方向竖状排列的小颗粒，此时，合金已完成动态再结晶。
关键字: 镍基高温合金；粉末冶金；等离子旋转电极制粉；热等静压；热挤压；原始颗粒边界
（1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. Research Institute of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:The superalloys powders were prepared by plasma rotating electrode processing (PREP). The powder was consolidated by hot isostatic pressing (HIP) and hot extrusion (HE). The microstructures of powders, as-HIPed and as-HEXed alloys were examined. The constitution, formation mechanism and the microstructure evolution of PPB during the hot extrusion were studied. The results show that some small size oxides enriched with Al and a layer of Zr, O, C concentrate on the surface of powder. The PPB is stracture of phases, MC carbides and Al2O3, Zr enriched oxides particles. The PPB formation mechanism is that, under the effect of temperature field, carbides, precipitates and oxides are more ready to precipitate at bonding interface. After hot extrusion, the big phases at PPB are gone and continuous PPB is broken. These particles aligned along extrusion direction are the remains of PPB (MC type carbides and trace amounts of oxides), and the dynamic recrystallization occurs during hot extrusion.
Key words: nickel-based superalloys; powder metallurgy; plasma rotating electrode processing; hot isostatic pressing; hot extrusion; prior particle boundry
