Metallurgy The Hall-Petch relationship links a metal's increasing hardness with decreasing grain size, but it breaks down when grains become very small. This is unfortunate because nanograined metals could otherwise be extremely hard. Hu et al. found a way to circumvent this problem in a set of nickel-molybdenum alloys. They altered the molybdenum composition and annealed the samples at just the right temperature, which stabilized the grain boundaries in their nanograined samples. This allowed hardness to keep increasing with decreasing grain size, which could provide a route for designing superhard coatings. Science , this issue p. [1292][1] [1]: /lookup/doi/10.1126/science.aal5166

中文翻译：

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纳米金属避免变软

冶金 Hall-Petch 关系将金属的硬度增加与晶粒尺寸减小联系起来，但当晶粒变得非常小时它就会分解。这是不幸的，因为否则纳米颗粒金属可能会非常坚硬。胡等人。在一组镍钼合金中找到了规避这个问题的方法。他们改变了钼的成分并在合适的温度下对样品进行了退火，这稳定了纳米晶粒样品中的晶界。这使得硬度随着晶粒尺寸的减小而不断增加，这可以为设计超硬涂层提供一条途径。科学，这个问题 p。[1292][1][1]：/lookup/doi/10.1126/science.aal5166