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Temperature-dependent material attrition and subsurface lattice damage of single-crystal AlN at various scratching depths/forces are investigated at atomic level using molecular dynamics simulation. An ultimate removal precision of depth down to monolayer of AlN is achieved based on the present temperature-dependent critical conditions. The number of worn atoms, positively influenced by temperature due to the reduction of hardness, increases exponentially with increasing normal force in the plastic domain. Archard-type wear coefficient K values calculated at different temperatures increase linearly with normal force, and the slope is independent of temperature. Independently of load and temperature, a wear coefficient normalized with the tangential contact area, K / A tang , is developed to interpret the removal efficiency of AlN substrate with diamond abrasive. • Temperature-dependent plastic removal of AlN was elucidated at atomic level via MD simulation. • Increasing temperature can promote wear of GaN primarily due to the reduction of hardness. • Atomic layer removal of AlN is realized over a wide temperature range. • Temperature-independent wear coefficient increases linearly with normal load. • A normalized wear coefficient, K / A tang , is developed to interpret the removal efficiency of AlN with diamond abrasive. [ABSTRACT FROM AUTHOR]

Tungsten (W) and W alloys are regarded as the most promising candidates for plasma facing materials (PFMs), which will be widely used in the next generation of fusion reactors. However, blistering in W-PFM induced by extremely high fluxes of low-energy hydrogen (H) and helium (He) ions irradiation will seriously influence the plasma stability and limits the lifetime of PFM. We systematically investigate the interaction between H and He interaction in W using molecular dynamics (MD) calculations. The vacancy clusters can capture a large amount of H/He, and the H-He-vacancy clusters have much higher binding energy to He than to H. The binding energy of H-He-vacancy clusters to vacancy/W is positive, and H-He-vacancy clusters have strong trapping of W atoms and vacancies. He will strongly affect the H behavior in W, He atoms and He cluster will trap H atoms, thereby preventing the diffusion of H in W. [ABSTRACT FROM AUTHOR]