The scarcity of carbon in high-entropy carbides is widely recognized to significantly affect their fabrication and performance. However, achieving both high hardness and plasticity in these carbides remains a formidable challenge. This study investigates the impact of carbon vacancies on the phase structure and mechanical properties of high-entropy carbides, particularly (HfZrNbTa)C (x = 1, 0.8, 0.6, or 0.5), utilizing density functional theory calculations and experimental analysis. Theoretical computations indicate a rock-salt structure for the carbides, with reduced cell parameters as carbon vacancies increase. Notably, carbides with lower carbon content exhibit softer characteristics, as evidenced by Pugh's ratio. Experimental fabrication and testing reveal a decrease in Vickers hardness with decreasing carbon content, attributed to changes in bonding types. Certain compositions, particularly (HfZrNbTa)C and (HfZrNbTa)C, display plastic behavior alongside high hardness, offering promising avenues for future research and design of high-entropy ceramics.

中文翻译：

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高压烧结制备的高熵碳化物的机械性能：碳化学计量的作用


人们普遍认为高熵碳化物中碳的稀缺会严重影响其制造和性能。然而，在这些碳化物中同时实现高硬度和塑性仍然是一个艰巨的挑战。本研究利用密度泛函理论计算和实验分析，研究了碳空位对高熵碳化物，特别是 (HfZrNbTa)C (x = 1、0.8、0.6 或 0.5) 的相结构和机械性能的影响。理论计算表明碳化物具有岩盐结构，随着碳空位的增加，晶胞参数降低。值得注意的是，碳含量较低的碳化物表现出较软的特性，如普格比率所证明的那样。实验制造和测试表明，由于粘合类型的变化，维氏硬度随着碳含量的降低而降低。某些成分，特别是 (HfZrNbTa)C 和 (HfZrNbTa)C，在高硬度的同时表现出塑性行为，为未来高熵陶瓷的研究和设计提供了有前景的途径。