(西北工業(yè)大學(xué) 應(yīng)用物理系，西安 710072)
摘 要: 在自由落體條件下研究三元Fe62.5Cu27.5Sn10合金的亞穩(wěn)相分離和凝固組織形成規(guī)律。結(jié)果表明：液相分離使得合金液滴在快速凝固過程中形成2~3層殼核組織和均勻彌散組織，其相組成為α-Fe固溶體和Cu3Sn金屬間化合物相。分析液滴內(nèi)部L2(富Cu)液相的運動特征發(fā)現(xiàn)，溫度梯度和濃度梯度所引起的Marangoni運動促進(jìn)殼核組織的形成，合金液滴的最終凝固組織由冷卻速率、過冷度和Marangoni運動共同決定。如果液滴直徑足夠小，快速冷卻能夠抑制液相分離，凝固組織演變?yōu)榈容S枝晶形態(tài)，其相組成為α-Fe固溶體和Cu2FeSn化合物。EDS分析顯示，初生α-Fe相在快速凝固過程中發(fā)生了顯著的溶質(zhì)截留效應(yīng)。
關(guān)鍵字: Fe-Cu-Sn合金；相分離；快速凝固；Marangoni運動
（Department of Applied Physics, Northwestern Polytechnical University, Xi’an 710072, China）
Abstract:Liquid ternary Fe62.5Cu27.5Sn10 alloy was rapidly solidified under free fall condition. The results show that the liquid phase separation leads to the formation of two- or three-layer core-shell structures and uniformly dispersed structures. These two types of microstructures are both composed of α-Fe and Cu3Sn phases. According to the movement characteristics of L2(Cu-rich) liquid phase, the thermal and solutal Marangoni migrations are the dynamic mechanisms responsible for the development of core-shell structure. The finally solidified microstructure of ternary Fe62.5Cu27.5Sn10 alloy depends on the combined effects of cooling rate, undercooling and Marangoni migration. If the droplet diameter is sufficiently small so that its high cooling rate suppresses the liquid phase separation, the solidification microstructure evolves into the equiaxed dendrite morphology. The dendritic microstructure is composed of α-Fe solid solution and Cu2FeSn intermetallic compound. EDS analysis reveals that α-Fe phase exhibits a remarkable solute trapping effect during containerless rapid solidification.
Key words: Fe-Cu-Sn alloy; phase separation; rapid solidification; Marangoni migration
