Xin Wu

As a critical strategic material for extreme environment applications, the surface integrity of single-crystal tungsten directly dictates the performance and reliability of functional devices. However, the damage evolution mechanisms of single-crystal tungsten during nanopolishing manufacturing processes have yet to be systematically explored. In this study, molecular dynamics simulations of nanopolishing were established to specifically investigate the mechanical properties, crystal defect evolution, and subsurface damage mechanisms under various initial surface roughness conditions at the nanoscale. The results reveal that surface roughness texture, acting as a key geometric constraint for material removal mechanisms, exerts a significant influence on atomic migration, cutting load fluctuations, and the distribution of subsurface stress fields. Meanwhile, the internal energy dissipation and dislocation density within the system exhibit trends of dynamic growth and non-linear oscillation. Furthermore, variations in the structural complexity of the surface texture lead to distinct shifts in the temperature rise patterns within the processing zone. This research elucidates the nanopolishing mechanisms induced by surface morphology from an atomic perspective, providing essential theoretical criteria and technical guidance for achieving high-efficiency and low-damage ultra-precision manufacturing of single-crystal tungsten.

Owing to its unique combination of properties, γ -TiAl alloy demonstrates remarkable advantages in high-temperature lightweight structural applications, establishing itself as a new critical material. However, the degradation mechanisms of material surface integrity at atomic-scale precision remain insufficiently investigated within existing machining systems. Based on molecular dynamics methodology, this research systematically investigates the influence of varying grinding parameters (depth and speed) on burr formation of γ -TiAl alloy during nanogrinding processes. The analysis elucidates the underlying correlations through multiple aspects: surface deformation, grinding force fluctuations, dislocation defects, and stress distribution. Simulation results demonstrate that employing higher grinding speeds in conjunction with reduced grinding depths enhances surface finish quality and minimizes material accumulation. However, due to complex dislocation dynamics, the evolution of exit burrs exhibits a non-monotonic behavior. A comprehensive analysis of surface deformation, forces, and defects indicates that, within the studied parameter range, a grinding speed of 400 m s ⁻¹ combined with a shallow grinding depth of 1 nm represents a favorable processing configuration. This work comprehensively reveals the formation mechanisms of surface burrs during nanogrinding of γ -TiAl alloys, establishing this mechanism as a fundamental basis in precision manufacturing applications of the alloy.