Self-Healing Metals

Designing self-healing in metals is a challenging task. Self-healing concepts successfully applied in polymers cannot be directly transferred because of different energetics. This has detained the field of self-healing metals, as evidenced by absolute publication numbers. Yet, relative publication numbers indicate a rapidly increasing interest in recent years triggered by the potential economic impact of advanced metallic materials. This chapter reviews all currently available self-healing concepts in bulk metallic materials. We provide a classification into two conceptually distinct routes: (1) autonomous self-healing of nanovoids at the nanoscale, aiming at a prevention of large-scale damage and (2) non-autonomous self-healing of macrocracks by an external trigger such as heat. The general idea of each self-healing concept is comprehensibly introduced, relevant publications are reviewed, and the characteristics of the concepts are compared. Finally, we discuss current constraints and identify the most promising concepts.