The influence of alloying in stabilizing a faceted grain boundary structure
The influence of alloying in stabilizing a faceted grain boundary structure
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DOI：
10.1016/j.actamat.2020.09.085
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发表时间：
2020-12
期刊：
影响因子：
9.4
通讯作者：
Jonathan L. Priedeman;G. Thompson
中科院分区：
文献类型：
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作者：
Jonathan L. Priedeman;G. Thompson
人们早就知道晶界结构取决于溶质和温度等因素。在这项工作中，采用原位原子尺度成像来观察 Pt-5Au（at.%）纳米晶合金中 Σ21a [1 1 1]-倾斜轴边界在 600∘C 和 800∘C 下的刻面。随着温度的升高，我们观察到从许多、较短的刻面到更少、更长的刻面的演变。通过基本区域形式，优选的面被显示为对称等效的倾斜边界。 Pt 双晶的模拟表明，这些优选晶面并不位于能量最小值（晶界取向错误可能进入的倾斜边界）；然而，Au 对这些晶界晶格位点的偏析焓的计算表明 Au 具有更大的偏好，降低了晶界能量，并解释了观察到的小面稳定性。
Grain boundary structures have long been known to depend on factors such as solutes and temperature. In this work,in-situatomic scale imaging was used to observe the faceting of a Σ21a [1 1 1]-tilt-axis boundary at 600∘C and 800∘C in a Pt-5Au (at. %) nanocrystalline alloy. With an increase in temperature, we observe an evolution from many, shorter facets to fewer, longer facets. The preferred facets are shown to be symmetrically equivalent tilt boundaries, via the fundamental zone formalism. Simulation of Pt bicrystals reveals that these preferred facets do not lie in an energy minimum (of the tilt boundaries that the grain boundary misorientation could access); however, calculation of the segregation enthalpy of Au to these grain boundary lattice sites indicates a greater preference of Au, reducing the grain boundary energy, and explaining the facet stabilization observed.