AI 中文总结
研究利用机器学习原子间势结合模拟，探究(MoCrTi)(100 - x)Alx难熔高熵合金的有序化，分析其热容量、短程有序参数及结构，确定有序化与机械刚度关系，为该合金设计提供指导。
AI 中文摘要
难熔高熵合金因其优异力学性能成为高温应用的候选材料。理解其化学有序化的热力学机制对优化性能至关重要。本文利用通用机器学习原子间势结合混合蒙特卡罗和分子动力学模拟，研究了(MoCrTi)(100 - x)Alx体系随温度变化的热力学和力学性能。热容量和短程有序参数揭示了不同的有序 - 无序转变行为。不同合金呈现不同转变阶段，结构分析表明低温有序B2相的亚晶格分布。还确定了有序化与机械刚度的关系，有序化显著增强弹性常数和模量且呈非单调成分依赖性。这些发现为成分、化学有序化和机械性能之间的相互作用提供了基本见解，为难熔高熵合金设计提供指导。
英文摘要
Refractory high-entropy alloys are promising candidates for high-temperature applications, yet the effects of composition on their chemical-ordering pathways and mechanical properties remain insufficiently understood. Here, a universal MLIP combined with MC and MD simulations is employed to investigate the temperature-dependent thermodynamic and mechanical behavior of (MoCrTi)(100-x)Alx alloys. Atomic configurations, sublattice occupations, and simulated diffraction intensities reveal pronounced B2-type chemical ordering at low temperatures, with Mo and Al occupying one sublattice and Cr and Ti occupying the other. The configurational heat capacities and SRO parameters further reveal a strong composition dependence of the ordering pathway. The Mo25Cr25Ti25Al25 and Mo32Cr32Ti32Al4 alloys exhibit a single dominant ordering stage involving cooperative changes in multiple B2-type pair correlations. By contrast, Mo28Cr28Ti28Al16 and Mo30Cr30Ti30Al10 exhibit two distinct ordering stages. Their low-temperature features are associated primarily with changes in the Mo-Al and Al-Al correlations, respectively, whereas their high-temperature features involve collective changes in the remaining B2-type pair correlations. Chemical ordering also fundamentally alters the composition dependence of mechanical stiffness. Whereas the elastic constants of disordered configurations increase approximately monotonically with decreasing Al content, those of the ordered configurations exhibit a non-monotonic dependence and reach a maximum in Mo30Cr30Ti30Al10. This anomalous enhancement originates from a SRO induced redistribution of atomic pairs, particularly Mo-Cr pairs. These results establish a direct atomistic connection among alloy composition, multistage chemical ordering, and mechanical stiffness, providing guidance for tuning the mechanical behavior of RHEAs through compositional control.
Comments23 pages, 10 figures, 58 references; revised & resubmitted manuscript
