The impact of alloying on defect-free nanoparticles exhibiting softer but tougher behavior.

The classic paradigm of physical metallurgy is that the addition of alloying elements to metals increases their strength. It is less known if the solution-hardening can occur in nano-scale objects, and it is totally unknown how alloying can impact the strength of defect-free faceted nanoparticles. Purely metallic defect-free nanoparticles exhibit an ultra-high strength approaching the theoretical limit.

Structural phase transformations in metallic grain boundaries.

Structural transformations at interfaces are of profound fundamental interest as complex examples of phase transitions in low-dimensional systems. Despite decades of extensive research, no compelling evidence exists for structural transformations in high-angle grain boundaries in elemental systems. Here we show that the critical impediment to observations of such phase transformations in atomistic modelling has been rooted in inadequate simulation methodology.

Relationship between equilibrium fluctuations and shear-coupled motion of grain boundaries.

We derive general analytical expressions relating the equilibrium fluctuations of a grain boundary to key parameters governing its motion coupled to shear deformation. We validate these expressions by molecular dynamics simulations for symmetrical tilt boundaries and demonstrate how they can be used to extract the misorientation dependence of the grain-boundary mobility. The results shed light on fundamental relationships between equilibrium and nonequilibrium grain-boundary properties and provide new means to predict those properties.