Metal defects can be eliminated by cyclic loading
It’s a well-known characteristic of metals that repeated bending in the same place can cause the material to weaken and eventually break; this phenomenon, known as metal fatigue, can cause serious damage to metal components subjected to repeated stress. But now, researchers from MIT, Carnegie Mellon University, Xi’an Jiaotong University, and elsewhere have found that under certain conditions, repeated slight stretching of nanoscale metal pieces can actually strengthen a material by eliminating defects in its crystalline structure. The new finding is reported this week in the Proceedings of the National Academy of Sciences, in a paper co-authored by MIT’s Ming Dao and Ju Li, Subra Suresh of Carnegie Mellon, Zhiwei Shan of Xi’an Jiaotong University, and others in China and at Johns Hopkins University. They refer to the new process as “cyclic healing.” “While metal fatigue has been studied extensively at larger volumes of materials, there has been little understanding of it at...