Intentional solute segregation at grain boundary (GB) can effectively stabilize the nanograined alloys by reducing the excess energy and mobility of GB, but it usually works for binary alloys with sufficient GB segregation tendency. Here, we found that the segregation of Cr can be enhanced in a nanostructured Fe-8Cr alloy with insufficient GB segregation tendency through the interaction of another solute Si (1.0 wt.%). After surface mechanical grinding treatment and subsequent annealing, the nanograined Fe-8Cr-1Si is more thermally stable than the nanograined Fe-8Cr, which is mainly attributed to the Si-enhanced Cr segregation as observed by Super-X energy-dispersive X-ray spectroscopy (EDS) mapping system. With the grain refinement to nanoscale, the thermal stability is further improved due to the increase of Cr content at GBs and the precipitates formed at appropriate high temperatures. The present finding provides guidance for the development of advanced nanostructured ternary alloys.

在晶界（GB）有意的溶质偏析可以通过降低GB的过剩能量和迁移率来有效地稳定纳米晶合金，但它通常适用于具有足够GB偏析倾向的二元合金。在这里，我们发现通过另一种溶质 Si (1.0 wt.%) 的相互作用，可以在 GB 偏析趋势不足的纳米结构 Fe-8Cr 合金中增强 Cr 的偏析。经过表面机械研磨处理和随后的退火处理后，纳米晶 Fe-8Cr-1Si 比纳米晶 Fe-8Cr 具有更高的热稳定性，这主要归因于 Super-X 能量色散 X 射线观察到的 Si 增强的 Cr 偏析光谱（EDS）绘图系统。随着晶粒细化到纳米级，由于GBs处Cr含量的增加以及在适当高温下形成的析出物，热稳定性进一步提高。目前的发现为先进纳米结构三元合金的开发提供了指导。