Soft metal micro/nanolubricant in tribology

•Reducing friction and wear are crucial mechanical components.•Soft metals for superior tribological performances.•Excellent prospects for tribology. Friction coefficient and wear rate are crucial performance indexes for the development of nanomaterials, which are of great significance for realizing energy conservation and prolonging service life of mechanical components. Herein, this review systematacially describes the latest progress on micro/nano-soft metal as effective reinforcements in the unitary, binary, ternary, and quaternary alloy matrix coatings/bulk materials, while providing the developments of soft metals serving as oil/grease additives for improving the anti-friction and wear resistant performances of unitary and binary alloys. Next, special superlubricity contributions of the soft metal micro/nano-materials in the unitary, binary, and ternary alloy systems are summarized. Additionally, we point out several problems existing in the applications of soft metal lubricants at this stage, and propose the possible solutions. Finally, the research prospects of soft metal micro/nano-lubricants in the field of tribology are prospected.