Ultrahardness: Measurement and Enhancement
Ultrahardness: Measurement and Enhancement
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DOI：
10.1021/acs.jpcc.5b00017
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发表时间：
2015-03
影响因子：
3.7
通讯作者：
Bo Xu;Yongjun Tian
中科院分区：
文献类型：
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作者：
Bo Xu;Yongjun Tian
在寻找硬度与天然金刚石相当甚至更高的新型超硬材料的过程中，两个问题是中心关注的问题：如何可靠地测量硬度以及如何提高硬度。在这里，我们分析了压痕硬度测量过程中压头和被测样品的具体应力状态，发现压头应比被测样品更硬的传统先决条件并不是确保可靠的硬度测量所必需的。事实上，只要样品的剪切强度小于金刚石压头的压缩强度，就可以可靠地测量压痕硬度。此外，我们建议纳米结构（纳米结晶度和纳米孪晶）作为提高硬度的有效手段。
In the quest for novel superhard materials with hardness comparable to or even higher than that of natural diamond, two issues are of central concern: how hardness can be reliably measured and how hardness can be enhanced. Here, we analyze the specific stress states of the indenter and the tested sample during an indentation hardness measurement and reveal that the traditional prerequisite that the indenter should be harder than the measured sample is not necessary to ensure a reliable hardness measurement. In fact, the indentation hardness can be reliably measured as long as the shear strength of the sample is less than the compressive strength of the diamond indenter. Also, we suggest nanostructuring (nanocrystallinity and nanotwinning) as an effect means of hardness enhancement.