Grain boundary structural transitions can lead to significant changes in the properties and performance of materials. In multi-principal element alloys, understanding these transitions becomes complex due to phenomena such as local chemical ordering and multi-component segregation. Using atomistic simulations, we explore a metastable-to-equilibrium grain boundary structural transition in NbMoTaW. The transition, characterized by structural disordering and reduced free volume, shows high sensitivity to its local chemical environment. Most notably, the transition temperature range of the alloy is more than twice that of a pure metal. Differences in composition between coexisting metastable and equilibrium structures highlight the change in local site availability due to structural relaxation. Further examination of grain boundaries with fixed chemical states at varying temperatures reveals that the amount of segregation significantly influences the onset temperature yet has minimal effect on the transition width. These insights underscore the profound effect of chemical complexity and ordering on grain boundary transitions in complex concentrated alloys, marking a meaningful advancement in our understanding of grain boundary behavior at the atomic level.

中文翻译：

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由于偏析和化学复杂性，NbMoTaW 中的亚稳态到平衡晶界结构转变受阻

晶界结构转变可以导致材料的性质和性能发生显着变化。在多主元素合金中，由于局部化学有序和多组分偏析等现象，理解这些转变变得复杂。通过原子模拟，我们探索了 NbMoTaW 中亚稳态到平衡晶界结构的转变。这种转变的特点是结构无序和自由体积减少，显示出对其局部化学环境的高度敏感性。最值得注意的是，该合金的转变温度范围是纯金属的两倍多。共存的亚稳态结构和平衡结构之间的组成差异凸显了由于结构松弛而导致的局部站点可用性的变化。对不同温度下具有固定化学态的晶界的进一步检查表明，偏析量显着影响起始温度，但对转变宽度的影响最小。这些见解强调了复杂浓缩合金中化学复杂性和有序性对晶界转变的深远影响，标志着我们对原子水平晶界行为的理解取得了有意义的进展。