Wang ZWang CZhao Y.-LKai J.-JLiu C.-THsueh C.-H.CHUN-HWAY HSUEH2021-08-052021-08-0520210042207Xhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85104414004&doi=10.1016%2fj.vacuum.2021.110249&partnerID=40&md5=89029863570071677a2decee4bbb57a8https://scholars.lib.ntu.edu.tw/handle/123456789/576900Designing a metal film with good toughness, high fatigue resistance and electrical resistivity is a daunting challenge for flexible electronic devices. Nanotwin strengthening is a possible way to solve this problem. Nanocrystalline CoCrFeMnNi high entropy alloy films (HEAFs) with high-density nanotwins were processed by magnetron sputtering in the present study. The films exhibited good toughness, high fatigue resistance and the electrical resistivity. The outstanding toughness could be attributed to nanotwins that constricted void initiation and crack propagation. The fatigue resistance was found to result from detwinning of nanotwins in nanograins during cyclic loading, and the high electrical resistivity was attributed to the retardation of electron movement by the high-density grain boundaries and severe lattice distortions. The findings showed that nanotwins could be used to tune the mechanical properties of HEAFs with the potential applications for flexible electronic devices in microelectromechanical systems. ? 2021 Elsevier LtdChromium alloys; Cobalt alloys; Electromechanical devices; Entropy; Fatigue of materials; Grain boundaries; High-entropy alloys; Iron alloys; MEMS; Metallic films; Nanocrystalline alloys; Nanocrystals; Thermoelectric equipment; Alloy film; Device application; Fatigue-resistance; Flexible electronics device; High entropy alloy film; High entropy alloys; Metal-films; Nano-twin strengthening; Nanotwinned; Nanotwins; Electric conductivityjournal article10.1016/j.vacuum.2021.1102492-s2.0-85104414004