Fe-C-Si合金凝固过程中石墨的球化机理研究  

Spheroidizing Mechanism of Graphite in Solidification of Fe-C-Si Alloy

作　　者：廖琳[1] 朱定一[1] 杨泽斌[1] 

机构地区：[1]福州大学材料科学与工程学院,福建福州350002

出　　处：《铸造》2009年第7期705-709,共5页Foundry

基　　金：国家自然科学基金资助项目(50471007);福建省自然科学基金资助项目(E0710006)

摘　　要：采用热分析试验方法研究了Fe-C-Si合金凝固过程中过冷度的变化对石墨生长形态的影响,探讨了石墨结晶时的再辉温差与石墨生长形态间的相互关系,通过座滴法研究了液固界面能对石墨生长形态的影响。结果表明,稀土元素Ce促使石墨球化的凝固特征是显著降低了形核温度,但在添加Ce的情况下,只要提供一个小的过冷条件,石墨形态将由球状转变为片状,这种转化完全依赖于结晶时过冷度的大小,这表明过冷度的大小是影响石墨生长方式和最终形态的关键因素之一。凝固曲线表明石墨以片状形态生长时的再辉温差大,以球状生长时较小,这反映了石墨以片状生长时的速度高于球状生长时的速度。同时液态合金在石墨(0001)基面上的液固界面能高,石墨趋于球状形态生长;在(1010)棱面上的液固界面能低,石墨趋于片状形态生长。Thermal analysis and sessile drop method were adopted to analyze the solidification process of Fe-C-Si alloy. The influence of the undercooling, the recalescence temperature difference of primary graphite nucleation, and the liquid-solid interface energy on the growth morphology of graphite in the process of solidification of Fe-C-Si alloy were investigated. The results show that the solidification characteristic of the graphite spheroidizing with Ce addition is characterized by the significant reduction in the nucleation temperature. However, even giving a small undercooling to the alloy with the Ce addition, the graphite morphology changed from sphericity to flake. This transformation is totally dependent on the degree of undercooling in the crystallization. So the nodulizer is not sufficient condition of graphite spheroidization, but undercooling is a primary factor that promotes the spheroidization of graphite during the solidification. The solidification curves also show that the recalescence temperature difference of flaky graphite is higher than that of spherical graphite, which reflects the growth speed of graphite, namely, the speed of flaky graphite is faster than that of spheroidal graphite. The liquid-solid interface energy on the （0001） surface is higher than that of （10^-10） surface, so the former growth morphology of graphite is spheroidal, the latter is flaky.

关 键 词：Fe-C-Si合金 球化机理 过冷 热分析 液固界面能 

分 类 号：TG131[一般工业技术—材料科学与工程]