【摘要】 研究了电磁场对团球γ+(Fe,Mn)3C共晶体增强奥氏体钢基自生复合材料(EAMC)中C、Mn元素的偏析及凝固组织的作用.结果表明,电磁场促进C、Mn元素的偏析;电磁场作用后,EAMC组织中的团球共晶体体积分数增加,在奥氏体基体中呈弥散分布;另外,在基体内出现内生的奥氏体晶粒,这是由于电磁搅拌作用下,初生奥氏体晶粒在发展过程中分枝断裂所致.运用电磁场理论与非平衡凝固理论分析了电磁场对EAMC组织影响的机制:电磁场作用的热与搅拌效应可以减小溶质的有效分凝系数keff,为初生奥氏体(γ-Fe)枝晶的充分分枝提供了时空条件以及热力学与动力学条件,有利于团球共晶体的生成与体积分数的增加.更多还原

【Abstract】 The results presented in this paper make a contribution to investigation of the effects of electromagnetic on the segregation of C and Mn elements and the microstructure of in-situ granular γ+（Fe,Mn）₃C eutectics reinforced steel matrix composites （abbreviated EAMC）. Electromagnetic can enhance the segregation of C and Mn elements. The volume fraction of the granular eutectics increases largely with the electromagnetic process during solidification. Endogenetic austenite crystals appear in the matrix of EAMC, which results from the rupture of the dendrite of the primary austenite crystals during growing. The mechanism of the effects of electromagnetic on the microstructure was analyzed with the electromagnetic theory and non-equilibrium solidification theory. The heating and stirring domino effects of electromagnetic decrease the efficient distribution coefficient (k_eff) of the solute in EAMC. It provides space-time, thermodynamics, and dynamics terms to the developed branching of primary austenite dendrites （γ-Fe）, which is beneficial to the formation and increasing volume fraction of the granular eutectics.更多还原