Vacancy Engineering in Metals and Alloys

TL;DR

Vacancy engineering involves controlling atomic vacancies in metals and alloys to tailor microstructures and enhance properties, offering new pathways for designing advanced materials.

Contribution

This review synthesizes recent advances in vacancy generation, modeling, and characterization, highlighting their role in microstructure evolution and material performance.

Findings

Vacancies can be generated through quenching, deformation, and additive manufacturing.

Controlling vacancies influences diffusion, precipitation, and phase stability.

Vacancy management enables microstructure optimization for various applications.

Abstract

Vacancy engineering, the intentional control of atomic-scale vacancies in metals and alloys, is emerging as a powerful yet underexplored strategy for tailoring microstructures and optimizing performance across diverse applications. By enabling excess vacancy populations through quenching, severe deformation, thermomechanical treatments, or additive manufacturing, new microstructures can be obtained that achieve unique combinations of strength, ductility, fatigue life, corrosion resistance, and conductivity. Vacancies are distinct among lattice defects: they are non-conserved entities essential for solute diffusion, yet variably coupled to solutes, dislocations, and phase boundaries. They can accelerate transformations such as nucleation and precipitation or retard kinetics when trapped in clusters, and their transient trapping and release can drive microstructural evolution across time and length scales. This Review synthesizes recent advances in generating, modeling, and characterizing vacancies, highlighting their role in diffusion, precipitation, and phase stability. Case studies in lightweight, high-temperature, fatigue-resistant, electrical, and biomedical materials demonstrate the broad potential of vacancy control. We conclude by emphasizing the opportunity for the metallurgical community to fully exploit excess vacancies as controllable, design-relevant defects that enable new pathways for microstructure and property optimization in next-generation alloys.