Elucidating the Mechanisms of Irradiation Induced Softening in Nanocrystalline BCC Metals

阐明纳米晶 BCC 金属的辐照诱导软化机制

• 批准号: 1810040
• 负责人: Jason Trelewicz
• 金额: $ 50万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1810040&HistoricalAwards=false
• 关键词: Elucidating; Mechanisms; Irradiation; Induced; Softening

NON-TECHNICAL DESCRIPTION: Coupled extremes of high stresses and irradiation necessitate new materials design methodologies for enhancing strength and radiation tolerance through precise control over material structure. Over the past two decades, nanocrystalline metals that contain a large fraction of internal interfaces have been pursued to address the performance limitations of traditional engineering alloys. These unique materials exhibit significant improvements in mechanical properties such as strength and wear resistance, but under certain irradiation conditions, develop internal defects that degrade these properties and limit their technological utility for extreme environment applications. Using an integrated computational and experimental framework, this research will build a fundamental understanding of the mechanisms responsible for such property degradations, specifically characterizing the intricate defect networks that produce softening and hardening in nanocrystalline metals under irradiation. Technologically, new insights into the impact of irradiation on the mechanical performance of nanocrystalline metals will foster innovations in materials design for extreme environments to advance next-generation nuclear technologies as safe, sustainable energy sources with drastically reduced environmental impacts. The integration of research activities into educational initiatives will advance the engagement of underrepresented students in materials science and provide curriculum enrichment for engineering majors through the establishment of a new materials science and engineering major at Stony Brook University. TECHNICAL DESCRIPTION: This research will elucidate the mechanisms responsible for the transition from softening to hardening in nanocrystalline body centered cubic (BCC) metals containing helium irradiation defects. The guiding hypothesis is nanoscale helium defects aggregated in grain boundaries act as stress concentrations that reduce the energetic barrier for grain boundary mediated dislocation nucleation, which in turn manifests as a softening effect that ultimately competes with classical irradiation hardening. The research team will combine atomistic simulations with in situ mechanical testing experiments and nanoindentation to explore the influence of helium irradiation defects on the fundamental deformation processes in the nanocrystalline BCC metals tungsten and iron. The competition between classical irradiation hardening found in coarse-grained polycrystalline metals and softening prevalent in nanocrystalline materials will also be explored by considering the coupling of intragranular defect loop damage with grain boundary defects in the deformation behavior. The manifestation of these mechanisms in the mechanical response will be quantified and used to build mechanism-property maps on the basis of collective interactions of deformation mechanisms with irradiation defects. From this research, the team will gain a new understanding of radiation effects and their implications for the mechanical performance of nanocrystalline BCC metals. A fundamental understanding of competing mechanisms due to coupled defect states will foster new innovations for combating mechanical property degradation from irradiation damage, thereby providing opportunities for interface engineering through synergistic alloying-by-design methodologies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术描述：高应力和辐射的耦合极端需要新的材料设计方法，通过精确控制材料结构来提高强度和辐射耐受性。在过去的二十年里，含有大部分内部界面的纳米晶金属一直在寻求解决传统工程合金的性能限制。这些独特的材料在强度和耐磨性等机械性能方面表现出显着的改进，但在某些辐照条件下，会产生内部缺陷，降低这些性能，并限制其在极端环境应用中的技术实用性。使用一个集成的计算和实验框架，这项研究将建立一个基本的理解负责这种性能退化的机制，特别是表征复杂的缺陷网络，在辐照下产生软化和硬化的纳米晶金属。从技术上讲，辐照对纳米晶金属机械性能影响的新见解将促进极端环境下材料设计的创新，以推动下一代核技术作为安全，可持续的能源，大大减少对环境的影响。将研究活动融入教育举措将促进材料科学代表性不足的学生的参与，并通过在斯托尼布鲁克大学建立新的材料科学与工程专业，为工程专业提供丰富的课程。 技术说明：本研究将阐明含氦辐照缺陷的纳米晶体心立方（BCC）金属从软化到硬化转变的机制。指导性假设是聚集在晶界中的纳米级氦缺陷作为应力集中，其降低了晶界介导的位错成核的能量势垒，这反过来又表现为最终与经典辐照硬化竞争的软化效应。该研究小组将联合收割机原子模拟与原位力学测试实验和纳米压痕相结合，以探索氦辐照缺陷对纳米晶BCC金属钨和铁的基本变形过程的影响。通过考虑变形行为中晶界缺陷与晶内缺陷环损伤的耦合，还将探讨在粗晶多晶金属中发现的经典辐照硬化与在纳米晶材料中普遍存在的软化之间的竞争。这些机制在机械响应中的表现将被量化，并用于构建基于变形机制与辐照缺陷的集体相互作用的机制-属性图。通过这项研究，该团队将对辐射效应及其对纳米晶BCC金属机械性能的影响有新的认识。由于耦合缺陷状态的竞争机制的基本理解将促进新的创新，以打击辐照损伤的机械性能退化，从而通过协同合金化的设计methodology.This奖项反映了NSF的法定使命接口工程提供了机会，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

项目成果

Revealing the synergistic effects of sequential and simultaneous dual beam irradiations in tungsten via in-situ TEM

• DOI: 10.1016/j.jnucmat.2020.152150
• 发表时间: 2020-09-01
• 期刊: JOURNAL OF NUCLEAR MATERIALS
• 影响因子: 3.1
• 作者: El-Atwani, O.;Cunningham, W. S.;Maloy, S. A.
• 通讯作者: Maloy, S. A.

Temperature threshold for preferential bubble formation on grain boundaries in tungsten under in-situ helium irradiation

• DOI: 10.1016/j.scriptamat.2020.01.013
• 发表时间: 2020-04-01
• 期刊: SCRIPTA MATERIALIA
• 影响因子: 6
• 作者: El-Atwani, O.;Cunningham, W. S.;Maloy, S. A.
• 通讯作者: Maloy, S. A.