Regulation of microstructural evolution and tribological performance of extruded magnesium matrix composites reinforced with nano-WS2

Extruded magnesium matrix composites reinforced with nano-sized tungsten disulfide were fabricated via powder metallurgy followed by hot extrusion, and their microstructural evolution, mechanical response, and tribological behavior were systematically investigated. Compared with monolithic magnesium, the incorporation of 0.5–2.0 wt% nano-reinforcement markedly altered dynamic recrystallization behavior during extrusion, resulting in pronounced grain refinement and texture modification. Electron backscatter diffraction analysis revealed that the average grain size decreased from approximately 8.5 µm in pure magnesium to about 3.2 µm at 2.0 wt% addition, accompanied by a reduction in basal texture intensity from 12.5 to 7.8 m.r.d. These microstructural changes translated into substantial strengthening, with Vickers hardness increasing from 58 to 92 HV0.1, yield strength from 135 MPa to 220 MPa, and ultimate tensile strength from 210 to 315 MPa, while maintaining elongation above 10%. Tribological tests under dry sliding against GCr15 steel demonstrated a pronounced reduction in friction and wear. The steady-state coefficient of friction decreased from ∼0.45 for unreinforced magnesium to ∼0.18 at 20 N for the composite containing 2.0 wt% reinforcement, and the corresponding wear rate was reduced by nearly one order of magnitude, from ∼1.8 × 10⁻⁴ to ∼1.5 × 10⁻⁵ mm³ Nm. Surface and debris analyses confirmed the formation of a continuous lubricious tribolayer that mitigated severe adhesive and abrasive wear. The results collectively demonstrate a clear composition–structure–property relationship, highlighting the effectiveness of nanoscale layered reinforcements combined with extrusion processing for achieving a balanced improvement in strength and wear resistance in lightweight metallic composites.