Alloying has long been used to confer desirable properties to materials. Typically, it involves the addition of relatively small amounts of secondary elements to a primary element. For the past decade and a half, however, a new alloying strategy that involves the combination of multiple principal elements in high concentrations to create new materials called high-entropy alloys has been in vogue. The multi-dimensional compositional space that can be tackled with this approach is practically limitless, and only tiny regions have been investigated so far. Nevertheless, a few high-entropy alloys have already been shown to possess exceptional properties, exceeding those of conventional alloys, and other outstanding high-entropy alloys are likely to be discovered in the future. Here, we review recent progress in understanding the salient features of high-entropy alloys. Model alloys whose behaviour has been carefully investigated are highlighted and their fundamental properties and underlying elementary mechanisms discussed. We also address the vast compositional space that remains to be explored and outline fruitful ways to identify regions within this space where high-entropy alloys with potentially interesting properties may be lurking.

合金化长期以来一直被用来赋予材料理想的性能。通常，它涉及在主要元素中添加相对少量的次要元素。然而，在过去的十五年中，一种新的合金化策略一直在流行，该策略涉及将多种主要元素以高浓度结合以产生新材料，即高熵合金。实际上，可以用这种方法解决的多维组成空间是无限的，到目前为止，仅研究了很小的区域。然而，已经显示出一些高熵合金具有超越常规合金的优异性能，并且将来可能会发现其他出色的高熵合金。这里，我们回顾了在了解高熵合金的显着特征方面的最新进展。重点研究了其行为已被仔细研究的模型合金，并讨论了它们的基本性能和潜在的基本机理。我们还将解决仍有待探索的巨大组成空间，并概述卓有成效的方法，以识别该空间中可能潜伏着潜在特性的高熵合金潜伏的区域。