论文标题
在添加剂制造中快速固化熔体池的快速凝固过程中，控制机制的切换
Switching of controlling mechanisms during the rapid solidification of a melt pool in additive manufacturing
论文作者
论文摘要
基于融合的金属添加剂制造（AM）是一种破坏性技术，可用于制造近网状的金属成分，并具有前所未有的出色性能组合。但是，AM处理与产生的微观结构之间的相互关系仍然不太了解。这在控制AM期间的微观结构开发以实现所需属性方面提出了巨大的挑战。在这里，我们使用专门为AM快速固化开发的相位场模型研究了单个熔体池的微观结构开发，即AM制造的金属组件的构件。发现在熔体池的快速凝固过程中，固液界面最初由溶质扩散控制，然后是热扩散控制阶段，其底层底层比冷冻范围大。控制机制的这种切换导致界面速度，溶质浓度和温度的突然变化，这完美地解释了在AM中观察到的各种异质微结构的形成。通过操纵处理条件，可以控制控制机制的切换以形成精制的微观结构或分层结构，以提高机械性能和抗裂纹的阻力。
Fusion-based metal additive manufacturing (AM) is a disruptive technology that can be employed to fabricate metallic component of near-net-shape with an unprecedented combination of superior properties. However, the interrelationship between AM processing and the resulting microstructures is still not well understood. This poses a grand challenge in controlling the development of microstructures during AM to achieve desired properties. Here we study the microstructure development of a single melt pool, the building block of AM-fabricated metallic component, using a phase-field model specifically developed for the rapid solidification of AM. It is found that during the rapid solidification of the melt pool, the solid-liquid interface is initially controlled by solute diffusion followed by a thermal diffusion-controlled stage with an undercooling larger than the freezing range. This switching of controlling mechanisms leads to the sudden changes in interfacial velocity, solute concentration, and temperature, which perfectly explains the formation of various heterogeneous microstructures observed in AM. By manipulating the processing conditions, the switching of controlling mechanisms can be controlled to form refined microstructures or layered structures for improved mechanical properties and resistance to cracking.
