In Situ Observation of the Competition Between Metastable and Stable Phases in Solidification of Undercooled Fe-17at. pctB Alloy Melt
In Situ Observation of the Competition Between Metastable and Stable Phases in Solidification of Undercooled Fe-17at. pctB Alloy Melt
复制标题
过冷 Fe-17at 凝固过程中亚稳相与稳定相竞争的原位观察。
DOI：
10.1007/s11661-015-3104-0
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发表时间：
2015
影响因子：
2.8
通讯作者：
Liu Feng
中科院分区：
文献类型：
--
作者：
Zhang Di;Xu Junfeng;Liu Feng
采用高速摄像技术研究了过冷Fe-17at.pctB合金熔体的凝固行为。Fe/Fe 3B（亚稳共晶）和Fe/Fe 2B（稳定共晶）之间的竞争生长与临界形核过冷度[=104 K（104 °C）]和临界生长过冷度[=151 K~183 K（151 °C~183 °C）]相关。对于初始过冷度，凝固过程中只发生稳定的共晶反应（L → Fe/Fe_2B），而对于初始过冷度，先发生亚稳共晶反应（L → Fe/Fe_3B），然后再发生稳定的共晶反应。然而，这并不能保证最终出现亚稳相（Fe 3B）。只有当亚稳共晶（Fe/Fe 3B）的生长速度大于稳定共晶（Fe/Fe 2B）时，才能在室温组织中发现Fe 3B相，否则，最终组织由Fe 2B和α-Fe组成。因此，不仅竞争形核，而且竞争生长也决定了Fe-17at.pctB合金的最终组织。
High-speed video (HSV) technique was used to investigate the solidification behavior of undercooled Fe-17at. pctB alloy melt. Competitive growth between Fe/Fe3B (metastable eutectic) and Fe/Fe2B (stable eutectic) was captured, which is correlated with the critical nucleation undercooling[=104 K (104 °C)] and the critical growth undercooling[=151 K~183 K (151 °C~183 °C)]. For the initial undercooling,, only the stable eutectic reaction (L → Fe/Fe2B) occurs during solidification, whereas, for, the metastable eutectic reaction (L → Fe/Fe3B) occurs firstly, followed by the stable eutectic reaction. Nevertheless,does not guarantee that the metastable phase (Fe3B) appears finally. Only if, Fe3B phase can be found in the room microstructure, as the growth velocity of metastable eutectic (Fe/Fe3B) is larger than stable eutectic (Fe/Fe2B) from HSV results; otherwise, the final structure consists of Fe2B and α-Fe. Accordingly, not only the competitive nucleation, but the competitive growth also determines the final microstructure of Fe-17at. pctB alloy.