Abstract Anomalous divergence of the pearlitic lamellae is typically observed during isothermal eutectoid transformation when the steel composition falls in the three-phase (austenite+ferrite+cementite) region. Here, the transformation progresses such that the composition of austenite changes continuously in the region ahead of the growing pearlite thus necessitating volume diffusion of Mn and resulting in a temporal increase in the interlamellar spacing as the growth kinetics becomes sluggish. In the present work, we develop a CALPHAD-informed multicomponent multiphase-field model to simulate the morphological evolution of pearlite in ternary Fe-2.46at.%C-3.50at.%Mn and Fe-2.51at.%C-5.40at.%Mn steels. Our phase-field simulations of lamellar growth capture the complex physics of multicomponent diffusion while provides in-depth insights into the mechanism of pearlitic divergence. Numerical investigations suggest that a temporal decrease in the driving force which is otherwise necessary to support manganese diffusion from the ferrite to cementite leads to lamellar divergence. Present investigations while showcasing the capabilities of our numerical approach enable the prediction of divergent pearlitic microstructure for a range of compositions and heat treatment cycles.

中文翻译：

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Fe-C-Mn钢珠光体发散的相场模拟

摘要 当钢成分落入三相（奥氏体+铁素体+渗碳体）区域时，等温共析转变过程中通常会观察到珠光体片层的异常发散。在这里，转变的进行使得在珠光体生长之前的区域中奥氏体的成分不断变化，因此需要 Mn 的体积扩散，并导致随着生长动力学变得缓慢，层间间距随时间增加。在目前的工作中，我们开发了一个基于 CALPHAD 的多组分多相场模型来模拟珠光体在三元 Fe-2.46at.%C-3.50at.%Mn 和 Fe-2.51at.%C-5.40at 中的形态演化。 %Mn 钢。我们对层状生长的相场模拟捕捉了多组分扩散的复杂物理学，同时提供了对珠光体发散机制的深入见解。数值研究表明，支持锰从铁素体扩散到渗碳体所需的驱动力随时间的推移而降低，导致层状发散。目前的研究展示了我们的数值方法的能力，能够预测一系列成分和热处理循环的发散珠光体微观结构。