Zhang Shengbiao, Li Chenyang, Mooraj Shahryar, Lai Yicheng, Patel Raj Sanjaykumar, Wu Margaret, Zhang Yanming, Ren Jie, Guan Shuai, Perron Aurelien, Yan Wentao, McKeown Joseph T, Xie Kelvin Y, Voisin Thomas, Chen Wei, Chen Wen
Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, MA, 01003, USA.
Department of Materials Design and Innovation, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA.
Adv Mater. 2025 Aug 27:e08659. doi: 10.1002/adma.202508659.
High-entropy alloys (HEAs) are promising candidates for advanced structural applications due to their excellent mechanical properties. Additive manufacturing (AM), with its rapid solidification conditions, enables the creation of unique nonequilibrium microstructures. To fully leverage the synergy between AM and HEAs, understanding how processing affects structure and properties is essential. Here, how solidification rate influences microstructure evolution and phase transformation pathway in laser additively manufactured AlCrFeNi eutectic HEAs is investigated. By increasing the laser scan speed and hence the solidification rate, distinct solidification modes evolving from coupled eutectic to anomalous eutectic and eventually to single-phase solidification are revealed. These transitions result in distinct microstructures and a wide range of mechanical properties. Thermodynamic modeling and molecular dynamics simulations reveal that low cooling rates allow for sufficient atomic diffusion and phase separation, facilitating coupled eutectic growth. In contrast, rapid cooling suppresses diffusion and destabilizes the solid-liquid interface, promoting anomalous or single-phase solidification. This integrated experimental and computational approach provides a multiscale understanding of solidification mechanisms in HEAs and underscores how kinetic effects can over-ride thermodynamic predictions under nonequilibrium conditions. These results demonstrate that AM can serve as a powerful tool to design HEAs with tailored microstructures and properties.
高熵合金（HEAs）因其优异的力学性能而成为先进结构应用的有前途的候选材料。增材制造（AM）具有快速凝固条件，能够创造独特的非平衡微观结构。为了充分利用AM和HEAs之间的协同作用，了解加工过程如何影响结构和性能至关重要。在此，研究了凝固速率如何影响激光增材制造的AlCrFeNi共晶高熵合金的微观结构演变和相变途径。通过提高激光扫描速度从而提高凝固速率，揭示了从耦合共晶到异常共晶并最终到单相凝固的不同凝固模式。这些转变导致了不同的微观结构和广泛的力学性能。热力学建模和分子动力学模拟表明，低冷却速率允许足够的原子扩散和相分离，促进耦合共晶生长。相反，快速冷却抑制扩散并使固液界面不稳定，促进异常或单相凝固。这种综合的实验和计算方法提供了对高熵合金凝固机制的多尺度理解，并强调了在非平衡条件下动力学效应如何超越热力学预测。这些结果表明，增材制造可以作为一种强大的工具来设计具有定制微观结构和性能的高熵合金。
