|About this Abstract
||2019 TMS Annual Meeting & Exhibition
||Solidification Processing of Light Metals and Alloys: An MPMD Symposium in Honor of David StJohn
||δ-γ transformation during / after δ dendritic solidification in Fe-C-Mn-Si alloys: time-resolved 2D / 3D imaging
||Hideyuki Yasuda, Takahiro Hashimoto, Naoki Sei, Kohei Morishita, Masato Yoshiya
|On-Site Speaker (Planned)
In Fe-C alloys (<0.5mass%C), it has been considered that the solidification of delta phase (BCC) was followed by the peritectic reaction, in which gamma phase (FCC) was produced from liquid and delta phases. Time-resolved and in-situ observation (transmission imaging) proved that delta phase transformed to gamma phase in the solid state. Namely, gamma phase was massively formed through the solid-state transformation (massive-like transformation). Recently, time-resolved tomography was developed to observe the solidification and the massive-like transformation. This technique allows us to observe evolution of solidification structure, to measure volume change due to transformation and to analyze crystallographic orientation relationship. In the massive-like transformation, 1) fine gamma grains are formed even in a single delta grains, 2) crystallographic orientation relationship was found, 3) coarsening of gamma grains occurred immediately after the massive-like transformation. Details of observations and mechanism of massive-like transformation will be discussed.