发表机构
Idaho National Laboratory; Texas A&M University（爱达荷国家实验室; 德克萨斯农工大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过离子辐照与相场建模，揭示稀Ni-X合金中辐照诱导晶界偏析的机制，发现Fe贫化、Cr竞争性输运、Mn热力学富集，并强调需综合处理多种因素。
AI 中文摘要
Ni基结构合金中晶界处的辐照诱导成分再分布对先进核反应堆的长期部署构成了关键挑战。由于缺陷介导的输运、热力学驱动力和竞争性微观组织陷阱在辐照下均可能发挥作用，控制溶质特异性偏析的机制仍知之甚少。我们在500、800和1000 K温度下对稀Ni-Fe、Ni-Cr和Ni-Mn二元合金进行了系统的Ni2+离子辐照至2 dpa，并使用STEM-EDS表征了晶界化学。偏析行为通过基于原子输运数据的速率理论相场建模进行解释。我们发现，Fe在所有温度下均通过优先空位-溶质交换（逆Kirkendall效应）在晶界处贫化。Cr的偏析反映了温度依赖的自间隙原子介导的向晶界输运与空位介导的远离晶界输运之间的竞争，在500 K时产生接近零的净偏析，在更高温度下产生贫化。相反，Mn表现出由热力学偏析主导的独特行为，驱动晶界处的局部富集。我们利用沿同一晶界的深度依赖表征，跨越辐照和未辐照区域，以分离辐照诱导和热力学贡献，并验证未辐照区域作为内部热力学参考。800 K下的空洞形成以及800和1000 K下的辐照诱导晶界迁移通过抑制和再分布溶质进一步增加了机制复杂性。我们结合实验和计算评估表明，解释辐照下晶界化学演化需要同时处理非平衡动力学输运、热力学驱动力、体陷阱效应和晶界迁移。
英文摘要
Radiation-induced composition redistribution at grain boundaries (GBs) in Ni-based structural alloys poses a critical challenge for the long-term deployment of advanced nuclear reactors. The mechanisms governing solute-specific segregation remain poorly understood because defect-mediated transport, thermodynamic driving forces, and competing microstructural sinks can all contribute under irradiation. We perform systematic Ni2+ ion irradiations on dilute Ni-Fe, Ni-Cr, and Ni-Mn binary alloys at 500, 800, and 1000 K to 2 dpa and characterize GB chemistry using STEM-EDS. The segregation behavior is interpreted using rate-theory phase-field modeling informed by atomistic transport data. We find that Fe depletes at GBs across all temperatures via preferential vacancy-solute exchange (inverse Kirkendall effect). Cr segregation reflects a temperature-dependent competition between self-interstitial atom (SIA)-mediated transport toward GBs and vacancy-mediated transport away from GBs, yielding near-zero net segregation at 500 K and depletion at higher temperatures. In contrast, Mn exhibits distinct behavior dominated by thermodynamic segregation that drives local enrichment at the GB. We leverage depth-dependent characterization along the same GB, spanning irradiated and unirradiated regions, to separate radiation-induced and thermodynamic contributions and validate the unirradiated region as an internal thermodynamic reference. Void formation at 800 K and irradiation-induced GB migration at 800 and 1000 K further add mechanistic complexity by suppressing and redistributing the solute. Our combined experimental and computational assessments show that interpreting GB chemistry evolution under irradiation requires concurrent treatment of non-equilibrium kinetic transport, thermodynamic driving forces, bulk sink effects, and GB migration.
