In functionally graded materials (FGMs) fabricated using directed energy deposition (DED) additive manufacturing (AM), cracks may form due to interdendritic stress during solidification, the formation of intermetallics, or the buildup of residual stresses. This study builds on our previously proposed concept of three-alloy FGM system feasibility diagrams for the identification of gradient pathways that avoid deleterious phases in FGMs by also considering solidification cracking. Here, five solidification cracking criteria were integrated into the feasibility diagrams, and equilibrium simulations were carried out based on Scheil results (termed Scheil-equilibrium simulation) to predict phase formation below the solidus temperature considering solidification microsegregation. The new feasibility diagrams were applied to four previously studied FGM systems, and the newly proposed approach predicted high crack susceptibility, detrimental phase formation, or interdendritic BCC phase formation in the experimentally observed cracking region. This demonstrates the utility of the proposed framework for crack prediction in the design of future FGMs gradient pathways.

中文翻译：

---

功能梯度材料的设计方法：考虑开裂的框架

在使用定向能量沉积 (DED) 增材制造 (AM) 制造的功能梯度材料 (FGM) 中，由于凝固过程中的枝晶间应力、金属间化合物的形成或残余应力的累积，可能会形成裂纹。本研究建立在我们之前提出的三合金 FGM 系统可行性图概念的基础上，用于通过同时考虑凝固开裂来识别避免 FGM 中有害相的梯度路径。在此，将五种凝固开裂准则整合到可行性图中，并根据 Scheil 结果进行平衡模拟（称为 Scheil 平衡模拟）以预测考虑凝固微偏析的固相线温度以下的相形成。新的可行性图应用于先前研究的四个 FGM 系统，新提出的方法预测了实验观察到的开裂区域中的高裂纹敏感性、有害相形成或枝晶间 BCC 相形成。这证明了所提出的裂纹预测框架在未来 FGM 梯度路径设计中的实用性。