(1. 中南大學 粉末冶金國家重點實驗室，長沙 410083；
2. 中南大學 粉末冶金研究院，長沙 410083)
摘 要: 采用等離子旋轉電極(PREP)法制備高溫合金粉末，通過熱等靜壓(HIP)和熱擠壓(HE)進行固結成型，對制備的粉末及HIP、HE態(tài)合金內部和表面顯微組織進行表征，探索鎳基高溫合金原始顆粒邊界(PPB)的組成、形成機制及組織演化特征。結果表明：合金在粉末態(tài)已發(fā)生元素偏析，粉末表層有細小的富Al氧化物顆粒，且顆粒表面有Zr、C、O元素的富集層；合金PPB主要為連續(xù)的大尺寸 相、MC型碳化物、Al2O3和富Zr的氧化物顆粒；PPB形成機制是在溫度場的作用下，碳化物、 相和氧化物易于在結合面析出，合金經熱擠壓后，原始顆粒邊界上大的 相完全消失，連續(xù)的PPB被破碎，形成含MC碳化物和少量氧化物的沿擠壓方向豎狀排列的小顆粒，此時，合金已完成動態(tài)再結晶。
關鍵字: 鎳基高溫合金；粉末冶金；等離子旋轉電極制粉；熱等靜壓；熱擠壓；原始顆粒邊界
（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
