In the context of the recent developments in the field of high entropy alloys (HEAs), CrFeNi based alloys with the addition of Al have gained significant attention due to their interesting combination of mechanical properties and corrosion resistance, enabling an even wider range of applications for HEAs. A key feature of this system is the co-existence of multiple phases such as body centered cubic (BCC) and face centered cubic (FCC) phase, which significantly enhances the mechanical performance of the alloy. However, despite the ongoing research efforts, an in-depth study of the effect of Al on the phase transformation kinetics in this system is not yet available, which undermines the design of effective heat treatments, curbing the optimization of microstructures and properties. In this work, the influence of 5 at.%Al addition on the interdiffusion behavior and phase transformation kinetics from FCC to BCC phase at 700 °C is studied by experiments and state-of-the-art phase field simulations. The kinetics of BCC precipitation are observed experimentally through the sequential characterization of samples heat treated up to 11 days. 2D phase field (PF) simulations of the growth and coarsening of BCC-precipitates in a dual-phase BCC/FCC system are performed on the same alloy system. Experimental observations reveal that the growth of BCC is greatly enhanced by the addition of Al to the ternary CrFeNi system. This result is consistent with findings from the phase field simulation. PF results show that the gradients of the diffusion potentials and interdiffusion mobilities are increased in the case of Al addition, which explains the significant increase of the phase transformation rate from FCC to BCC. Finally, the cross terms in multi-component diffusion equations are found to significantly affect the evolution of the phases. These findings demonstrate the need of multicomponent models to fully understand the complex interdiffusion behavior in high and medium entropy alloys to foster the design of these materials.

在高熵合金 (HEAs) 领域的最新发展背景下，添加 Al 的 CrFeNi 基合金由于其机械性能和耐腐蚀性的有趣组合而获得了极大的关注，这使得其应用范围更广。 HEA。该系统的一个关键特征是多相共存，如体心立方 (BCC) 和面心立方 (FCC) 相，这显着提高了合金的机械性能。然而，尽管正在进行研究工作，但尚未深入研究 Al 对该体系中相变动力学的影响，这破坏了有效热处理的设计，抑制了微观结构和性能的优化。在这项工作中，影响 5 at。通过实验和最先进的相场模拟，研究了 700 °C 下从 FCC 到 BCC 相的相互扩散行为和相变动力学的 %Al 添加量。BCC 沉淀的动力学通过对热处理长达 11 天的样品的顺序表征进行实验观察。双相 BCC/FCC 系统中 BCC 沉淀物的生长和粗化的 2D 相场 (PF) 模拟在同一合金系统上进行。实验观察表明，在三元 CrFeNi 体系中加入 Al 大大促进了 BCC 的生长。该结果与相场模拟的结果一致。PF 结果表明，在添加 Al 的情况下，扩散电位和相互扩散迁移率的梯度增加，这解释了从 FCC 到 BCC 的相变速率显着增加。最后，发现多组分扩散方程中的交叉项显着影响相的演变。这些发现表明需要多组分模型来充分了解高熵和中熵合金中复杂的相互扩散行为，以促进这些材料的设计。