University of Illinois at Urbana-Champaign, Urbana, IL, USA.
University of California, Santa Barbara, CA, USA.
Science. 2022 Sep 2;377(6610):1065-1071. doi: 10.1126/science.abn0392. Epub 2022 Sep 1.
Metallic materials experience irreversible deformation with increasing applied stress, manifested in localized slip events that result in fatigue failure upon repeated cycling. We discerned the physical origins of fatigue strength in a large set of face-centered cubic, hexagonal close-packed, and body-centered cubic metallic materials by considering cyclic deformation processes at nanometer resolution over large volumes of individual materials at the earliest stages of cycling. We identified quantitative relations between the yield strength and the ultimate tensile strength, fatigue strength, and physical characteristics of early slip localization events. The fatigue strength of metallic alloys that deform by slip could be predicted by the amplitude of slip localization during the first cycle of loading. Our observations provide a physical basis for well-known empirical fatigue laws and enable a rapid method of predicting fatigue strength as reflected by measurement of slip localization amplitude.
金属材料在施加的应力增加时会经历不可逆转的变形，表现为局部滑移事件，这些事件在反复循环时导致疲劳失效。通过在循环的早期阶段以纳米分辨率考虑单个材料的大体积的循环变形过程，我们从大量面心立方、六方密排和体心立方金属材料中辨别出了疲劳强度的物理起源。我们确定了屈服强度与极限拉伸强度、疲劳强度和早期滑移定位事件的物理特性之间的定量关系。通过在加载的第一个循环期间测量滑移定位的幅度，可以预测通过滑移变形的金属合金的疲劳强度。我们的观察结果为著名的经验疲劳定律提供了物理基础，并为通过测量滑移定位幅度来预测疲劳强度提供了一种快速方法。
