Maintaining Grain Boundary Segregation-Induced Strengthening Effect in Extremely Fine Nanograined Metals

Reinforcing grain boundaries through solute segregation is a promising strategy to strengthen nanograined metals. However, maintaining strengthening in extremely fine nanograined metals poses challenges due to grain size reduction and grain boundary structural changes from excessive segregation. This study employs hybrid Monte Carlo/Molecular Dynamics simulations to investigate the interplay between solute concentration, grain boundary structure, deformation mechanism, and strength in Zr-segregated nanograined Cu. Results exhibit significant strength enhancement by optimizing segregation, extending the strengthening effect to a grain size as small as 3.75 nm. Continuous Zr segregation induces a progressive transition from original grain boundaries to segregated and ultimately amorphous grain boundaries. Amorphization alters the dominant deformation mechanism from grain boundary migration to homogeneous shear-transformation-zone activation, fostering and optimizing the strengthening effect in extremely fine nanograined Cu. These findings inspire a novel approach of segregation-induced grain boundary amorphization to leverage strong boundaries and extremely fine nanograins for strengthening nanograined metals.