CAREER: Leveraging Plastic Deformation Mechanisms Interactions in Metallic Materials to Access Extraordinary Fatigue Strength.

非技术总结：结构工程中使用的金属材料对许多行业都至关重要。然而，许多金属和合金表现出有限的耐重复负荷（疲劳），限制了它们的可持续性。金属材料在反复加载下会发生纳米尺度的局部变形，最终导致裂纹萌生和断裂。在极端温度下的预变形在本项目中使用，以产生初始变形状态，阻碍在重复加载下的变形的局部化。首先，确定了极端温度下纳米尺度下金属材料的变形行为。然后，通过这种基本的理解，从极端的温度变形，阻碍变形的局部化时，材料受到反复加载的变形状态被识别。这一奋进旨在使当前的金属和合金具有竞争优势和可持续性，以满足我们社会不断发展的需求和先进的技术。技术摘要：该研究计划旨在探索和确定金属材料中塑性变形机制的相互作用。通过关注有益的相互作用，可以在面心立方材料中实现显著的疲劳强度。这个项目将探讨当各种变形机制竞争时，塑性如何局部化。国家的最先进的原位表征工具，善于统计和定性确定塑性局部化，是用来研究金属材料内的可能的变形机制相互作用的阵列。在此基础上，在极端温度下的预变形路径被引入到创建初始塑性局部化状态，阻碍循环不可逆性，一个因素，管理材料疲劳断裂。通过在极端温度下的变形，在纳米尺度上控制塑性局部化，结构金属的疲劳强度显著提高。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARY:Metallic materials used in structural engineering are vital to a wide range of industries. However, many metals and alloys exhibit limited resistance to repeated loading (Fatigue), limiting their sustainability. Metallic materials under repeated loading localize deformation at the nanometer scale that ultimately leads to crack initiation and fracture. Pre-deformation under extreme temperatures is used in the present project to generate initial deformation states that hinder the localization of the deformation under repeated loading. First, the deformation behavior of metallic materials at the nanometer scale under extreme temperatures is determined. Then, through this fundamental understanding, deformation states from extreme temperature deformations that hinder the localization of the deformation when the material is subject to repeated loading are identified. This endeavor aims to equip current metals and alloys with the competitive edge and sustainability required to meet the ever-evolving needs of our society and advancing technology.TECHNICAL SUMMARY:The research initiative seeks to explore and identify the interactions of plastic deformation mechanisms in metallic materials. By focusing on beneficial interactions, remarkable fatigue strength in face-centered cubic materials can be achieved. This project will explore how plasticity localizes when various deformation mechanisms compete. State-of-the art in-situ characterization tools, adept at statistically and qualitatively determining plastic localization, is used to study the array of possible deformation mechanism interactions within metallic materials. Building on this knowledge, pre-deformation pathways at extreme temperatures are introduced to create initial plastic localization states that hinder cyclic irreversibility, a factor that governs material fracture under fatigue. By manipulating plastic localization at the nanoscale through deformation at extreme temperatures, the fatigue strength of structural metals is enhanced dramatically.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.