Mechanical behavior of microstructurally stable nanocrystalline alloys: Processing, properties, performance, and prospects

Abstract

This review presents a comprehensive overview of the scientific revolution enabled by recent emergence of structurally stabilized NC materials. It captures major breakthroughs in achieving nanoscale stability through thermodynamic and kinetic pathways, and critically examines the fundamental mechanisms underpinning the stabilization, including GB segregation, solute drag, Zener pinning, and nanocluster formation. It describes how stabilization of NC materials can enable unprecedented access to their intrinsic mechanical and physical behaviors, revealing phenomena previously inaccessible due to the microstructural evolution during testing. Examples include superlative strength-ductility synergy, infinite fatigue endurance limits, creep resistance rivaling single crystals, radiation damage tolerance, and evidence of defect-mediated self-healing. The review also explores how stabilized NC materials challenge long-held assumptions about the mechanisms of deformation, recrystallization, and phase transformations. It further examines how stabilized NC alloys have revolutionized our theoretical understanding of these mechanisms and created new avenues for their fabrication as well as industrial applications. While significant challenges remain with scalable fabrication processes and standardization, we outline new design principles, manufacturing pathways, and strategic directions for future exploration and application frontiers that are poised to overcome long-standing limitations making structurally stabilized NC materials as a transformative class of structural materials for extreme environments and advanced technologies.