Tribological behavior of nanostructured AlSi10Mg fabricated by laser powder bed fusion/high-pressure torsion hybrid

The hybrid laser powder bed fusion/high-pressure torsion (LPBF/HPT) approach has emerged as an effective method to enhance the mechanical properties of metals/alloys via the ultrafine and/or nanoscale grain refinement route. However, most studies on this approach have largely focused on the investigation of microstructure and mechanical properties, while studies on tribological performance are significantly limited despite its importance in many engineering applications. Thus, in this study, the tribological behavior of a nanostructured AlSi10Mg alloy (AlSi10Mg being a critical material for key automotive components) fabricated by the hybrid LPBF/HPT approach is investigated for the first time. The results of dry sliding wear tests conducted in reciprocating linear pin-on-disk mode demonstrate enhancement in the tribological performance after HPT processing, as indicated by the comprehensive reductions in coefficient of friction (COF), mass loss, m, and specific wear rate, k values with increasing number of HPT revolutions, amounting to improvements of ~ 25, ~ 64, and ~ 71%, respectively, after 10 revolutions relative to the as-received condition. The overall enhanced tribological performance can be ascribed to the significantly high hardness attained due to the extreme grain refinement resulting from the HPT-imposed torsional strains.