铁碳合金中类块状δ-γ转变引起的枝晶破碎

Dendrite fragmentation induced by massive-like δ-γ transformation in Fe-C alloys.

作者信息

Yasuda Hideyuki, Morishita Kohei, Nakatsuka Noriaki, Nishimura Tomohiro, Yoshiya Masato, Sugiyama Akira, Uesugi Kentaro, Takeuchi Akihisa

机构信息

Department of Materials Science and Engineering, Kyoto University, Sakyo, Kyoto, 606-8501, Japan.

Department of Materials Science and Engineering, Kyushu University, Nishi-ku, Fukuoka, 819-0395, Japan.

出版信息

Nat Commun. 2019 Jul 18;10(1):3183. doi: 10.1038/s41467-019-11079-y.

DOI:10.1038/s41467-019-11079-y

PMID:31320622

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC6639379/

Abstract

Dendrite arm fragmentation is considered in solidification structure tailoring. Time-resolved and in situ imaging using synchrotron radiation X-rays allows the observation of dendrite arm fragmentation in Fe-C alloys. Here we report a dendrite arm fragmentation mechanism. A massive-like transformation from ferrite to austenite rather than the peritectic reaction occurs during or after ferrite solidification. The transformation produces refined austenite grains and ferrite-austenite boundaries in dendrite arms. The austenite grains are fragmented by the liquid phase that is produced at the grain boundary. In unidirectional solidification, a slight increase in temperature moves the ferrite-austenite interface backwards and promotes detachment of the primary and secondary arms at the δ-γ interface via a reverse peritectic reaction. The results show a massive-like transformation inducing the dendrite arm fragmentation has a role in formation of the solidification structure and the austenite grain structures in the Fe-C alloys.

摘要

枝晶臂破碎在凝固组织剪裁中受到关注。利用同步辐射X射线进行的时间分辨原位成像能够观察铁碳合金中的枝晶臂破碎现象。在此我们报道一种枝晶臂破碎机制。在铁素体凝固期间或之后，发生了从铁素体到奥氏体的块状转变而非包晶反应。这种转变在枝晶臂中产生了细化的奥氏体晶粒和铁素体 - 奥氏体边界。奥氏体晶粒被在晶界处产生的液相破碎。在单向凝固过程中，温度的轻微升高会使铁素体 - 奥氏体界面向后移动，并通过逆包晶反应促进δ - γ界面处一次和二次枝晶臂的分离。结果表明，引发枝晶臂破碎的块状转变在铁碳合金凝固组织和奥氏体晶粒组织的形成中发挥作用。