Effect of ultrasonic nanocrystal surface modification on microstructural evolution and tribological properties of pure tungsten

The effects of the ultrasonic nanocrystal surface modification (UNSM) treatment on the microstructure, mechanical properties, and tribological behavior of the pure tungsten (W) were investigated. The tribological properties of W were evaluated under dry sliding conditions and the coefficient of friction (COF) was reduced from 0.62 for the untreated sample to 0.5 and 0.42 after the UNSM treatment with reference and optimized conditions, respectively. A significant improvement of 38% in the wear resistance was achieved for the UNSM treatment with optimized conditions. It was found that the wear mechanisms shift from severe abrasive and adhesive wear to primarily mild abrasive wear with a substantial reduction in wear severity. • UNSM was employed to improve the surface properties of pure W for the first time • The maximum depth of the deformation layer was achieved through optimized ampltude • Progressive dynamic recrystallizations were explored as grain refinement mechanisms • UNSM led to surface hardening, compressive residual stress and XRD peak broadening • UNSM reduced friction coefficient, wear rate and severity of abrasive wear