CrMnFeCoNi纳米晶温度相关的拉伸行为研究

摘要：高熵合金是一种由多种主元元素组成的新型合金。实验研究表明等原子比CrMnFeCoNi高熵合金在低温下具有比室温更高的拉伸强度和断裂韧性。本文针对这一现象，利用分子动力学模拟对平均晶粒尺寸为6 nm的CrMnFeCoNi纳米晶在300、200和77 K下分别进行拉伸模拟。模拟研究揭示了纳米尺度CrMnFeCoNi高熵合金力学行为的温度效应和强韧机理。微结构演化分析表明：低温下，塑性变形阶段，滑移系开动的较少，位错滑移所受的阻力越大，屈服强度和抗拉强度越大；模型破坏时，孔洞缺陷形核较慢，更多孔洞缺陷演化成断口，更多的断口分摊拉伸应变，使得高熵合金纳米晶的低温韧性更好。

Temperature-dependent Tensile Behavior of CrMnFeCoNi Nanocrystals

Abstract: High-entropy alloys are a new type of alloys composed of several principal elements (usually ≥5) with equiatomic or near equiatomic ratios. Experimental studies have shown that the CrMnFeCoNi high-entropy alloy has higher tensile strength and fracture toughness at room temperature than at lower temperatures. In this paper, we performed molecular dynamics simulations to investigate the tensile behavior of the nanocrystalline CrMnFeCoNi alloy with an average grain size of 6 nm at 300, 200, and 77 K, respectively. The temperature effect and toughening mechanism of nano-scale CrMnFeCoNi high-entropy alloys were revealed. Microstructure evolution analyses show that in the plastic deformation stage at low temperatures, the slip systems were less activated. With the resistance of dislocation slip increases, the yield and tensile strengths increase. When the simulation cell collapses upon deformation, the nucleation of void defects is slower; More void defects evolve into fracture, and more fracture surfaces distribute tensile strain, which makes the low-temperature toughness of nanocrystalline high-entropy alloys better.