A Review of Self-healing Metals: Fundamentals, Design Principles and Performance

Self-healing metals possess the capability to autonomously repair structural damage during service. While self-healing concepts remain challenging to be realized in metals and metallic systems due to the small atomic volume of the mobile atoms, the slow diffusion unless at high temperatures and the strong isotropic metallic bonds, the scientific interest has increased sharply and promising progress is obtained. This article provides a comprehensive and updated review on the developments and limitations associated with the various modes of potentially healable damage induced in metals and alloys, i.e., stress-induced damage, irradiation-induced damage in bulk materials and contact damage in corrosion protective coatings. The spontaneous intrinsic healing mechanisms not requiring external assistance other than the material operating at the right temperature and an assisted healing mechanism with external intervention are reviewed. Promising strategies to achieve self-healing in metals are identified. Finally, we give some prospects for future research directions in self-healing metals.