Room-Temperature Electrochemical Healing of Fractured Metals

Repairing fractured metals to extend their useful lifetimes advances sustainability and mitigates carbon emissions from metal mining and processing. While high-temperature techniques are being used to repair metals, the increasing ubiquity of digital manufacturing and “unweldable” alloys, as well as the integration of metals with polymers and electronics, call for radically different repair approaches.<br/>This work presents a framework for effective room-temperature repair of fractured metals using an area-selective nickel electrodeposition process referred to as electrochemical healing. Based on a model that links geometric, mechanical, and electrochemical parameters to the recovery of tensile strength, this framework enables 100% recovery of tensile strength in nickel, low-carbon steel, two “unweldable” aluminum alloys, and a 3D-printed difficult-to-weld shellular structure using a single widely used nickel sulfamate electrolyte. Through a distinct energy-dissipation mechanism, this framework also enables up to 136% recovery of toughness in an aluminum alloy. Remarkably, this framework demonstrates that the restoration of tensile strength can be insensitive to nickel-metal adhesion, thus obviating the need for acid pre-treatments or multi-electrolyte processes.<br/>To facilitate practical adoption, this work reveals scaling laws for the energetic, financial, and time costs of repairing fractured metal parts from the microscale to the meter scale. This framework could potentially enable a universal and scalable approach to repair fractured metals at various length scales and in diverse applications. Electrochemical healing could open exciting possibilities such as electrically controlled autonomous and preemptive repair, as well as enable 3D-printed metal structures optimized for repair through designed failure characteristics.