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Chinese researchers solve world-class challenge in metal fatigue resistance 2025-04-11 Reporters learned from the Institute of Metal Research, Chinese Academy of Sciences, that an international research team led by Lu Lei’s group at the Shenyang Materials Science **Research Center has recently published new findings in the journal Science. For the first time, they achieved a balance among the strength, plasticity, and stability of metal materials, providing a revolutionary solution for ensuring the long-term performance of critical components in extreme environments across industries such as aerospace and energy chemistry. At 10,000 meters in altitude, the turbine blades of aircraft engines are subjected to tens of thousands of impacts of high temperature and pressure per second ； On cross-sea bridges, the main cables of suspension bridges must bear dynamic loads in the order of millions of tons throughout the year. The safe operation of these critical infrastructure elements is constantly challenged by the problem of fatigue failure of metal materials under cyclic loads. In the world of metals, there is an \"impossible triangle\": strength, ductility, and stability during use. Strength makes metals solid, ductility allows them to be shaped into various forms, while stability ensures they do not fail over time. However, it is often difficult to have all three of these characteristics simultaneously. The reason for metal instability is the presence of defects in the metal known as dislocations. When a metal is subjected to unidirectional stress, these dislocations move and accumulate, gradually leading to irreversible deformation and cracks, which ultimately result in sudden fracture – this is what is referred to as \"ratchet damage\". This type of damage undermines the stability of the material; it’s like a chronic disease of metals – not easy to detect, but with serious consequences. By introducing a spatially gradient ordered dislocation cell structure into conventional 304 austenitic stainless steel, researchers increased the material’s yield strength by 2.6 times. At the same time, compared to stainless steels and other alloys with similar strength levels, its average ratcheting strain rate was reduced by 2 to 4 orders of magnitude, thereby overcoming the bottleneck in improving the resistance of structural materials to ratcheting damage. Introducing a spatially gradient-ordered dislocation cell structure is akin to \"twisting a spiral.\" By controlling specific process parameters for the repeated twisting of the metal, researchers can create a stable dislocation cell structure with a spatially gradient distribution within it; this structure can hinder the movement of dislocations, acting as a carefully designed three-dimensional \"collision-proof wall\" network at the submicron scale embedded within the metal material. When an external force strikes, these \"impact barriers\" can absorb deformation energy like springs, and they can also trigger miraculous structural transformations at the atomic level. Within the network, even denser and finer \"impact barriers\" are formed, thousands of times thinner than a human hair; it’s as if nanoscale \"shock absorbers\" that can repair themselves are inserted into the metal’s structural framework, endowing the metal with the amazing ability to become stronger in the face of greater forces ； What’s even more remarkable is that the entire strengthening process occurs evenly, preventing damage caused by localized deformation. As a highly versatile toughening strategy, this gradient dislocation structure shows great potential for application in various engineering alloy materials, and it is expected to play an important role in ensuring the long service life and high reliability of critical components in extreme environments such as those in aerospace applications.