In superhard materials research, two topics are of central focus. One is to understand hardness microscopically and to establish hardness models with atomic parameters, which can be used to guide the design or prediction of novel superhard crystals. The other is to synthesize superhard materials with enhanced comprehensive performance (i.e., hardness, fracture toughness, and thermal stability), with the ambition of achieving materials harder than natural diamond. In this review, we present recent developments in both areas. The microscopic hardness models of covalent single crystals are introduced and further generalized to polycrystalline materials. Current research progress in novel superhard materials and nanostructuring approaches for high-performance superhard materials are discussed. We also clarify a long-standing controversy about the criterion for performing a reliable indentation hardness measurement.

中文翻译：

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超硬材料的最新进展

在超硬材料研究中，有两个主题是重点。一是从微观上了解硬度，建立具有原子参数的硬度模型，可用于指导新型超硬晶体的设计或预测。另一种是合成综合性能（即硬度、断裂韧性和热稳定性）增强的超硬材料，以实现比天然金刚石更硬的材料。在这篇评论中，我们介绍了这两个领域的最新发展。共价单晶的微观硬度模型被引入并进一步推广到多晶材料。讨论了新型超硬材料和高性能超硬材料的纳米结构方法的当前研究进展。