Nature Materials, Published online: 16 January 2026; doi:10.1038/s41563-025-02459-5The non-equilibrium processing conditions inherent to additive manufacturing produce metals with unique microstructures and mechanical properties that are often unattainable through conventional routes. This Review provides an overview of distinctive mechanical behaviours and deformation mechanisms that arise from these characteristic microstructures, and discusses critical needs and emerging opportunities for alloy design and processing control to achieve exceptional mechanical properties in additively manufactured metals.