Modeling mechanical alloying: A systematic review for materials science applications

Mechanical alloying is a key method for producing nanostructured metals, alloys, and composites with enhanced properties. The discrete element method (DEM) has become a powerful process-scale tool for resolving media motion, collisions, energy transfer, and particle–wall interactions. However, conventional DEM does not directly predict powder breakage, permanent deformation, cold welding, defect generation, chemical mixing, or phase evolution. These outcomes require calibrated breakage, constitutive, thermal, or multiscale material-response models. This review critically assesses DEM frameworks and complementary finite-element, atomistic, kinetic Monte Carlo, first-principles, and thermodynamic approaches that connect mill-scale loading to materials-science outcomes. DEM-only formulations and their coupling with population balance models, probability-based breakage models, and sub-DEM methods are examined in terms of their capabilities, limitations, required parameters, and experimental validation. These extensions use DEM-derived stressing statistics to estimate particle-size evolution, fracture, deformation, and accumulated strain beyond the short times directly simulated. Couplings with computational fluid dynamics and smoothed particle hydrodynamics are evaluated for wet milling, where fluid–particle interactions modify media motion, energy dissipation, and breakage. Thermal models are also reviewed, including frictional heat generation, contact conduction, environmental heat transfer, and behavior relevant to cryomilling. Particular attention is also given to calibration and validation of DEM parameters, including restitution, friction, breakage, and material constants. Finally, key challenges are identified in scaling DEM to industrial timeframes, integrating multiscale models, and bridging predictions with experiments, thereby offering a roadmap for more predictive materials processing.