Enhancing the elevated temperatures tribological properties of Al–Mg2Si composites by in-situ addition of Ti-based intermetallics and hot working

Abstract

Dry-sliding wear and friction behaviors of Al–15Mg2Si–5TiB2–4TiAl3 in-situ hybrid composites were evaluated at different temperatures (100–300 °C) and loads (10–60 N). The addition of TiB2 and TiAl3 particles enhanced the wear resistance. Moreover, the severe wear transition condition was changed from 300 °C to 10 N for the as-received Al–15Mg2Si composite to 300 °C - 60 N for the as-cast Al–15Mg2Si–5TiB2–4TiAl3 hybrid composite. This change was ascribed to the presence of thermostable particles and refined/modified Mg2Si particles via nucleation mechanism. Applying thermomechanical processing and hot deformation by the extrusion process necessitated higher loads and temperatures for this transition. Indeed, fragmentation and more homogeneous dispersion of reinforcements, higher hardness and toughness of composite due to grain refinement by dynamic recrystallization (DRX), reduction and closure of casting defects, and stability of tribolayer were recognized as leading reasons for replacing severe adhesive/plastic deformation wear with the abrasive mechanism. Accordingly, this study introduced an Al matrix hybrid composite with excellent performance at elevated temperatures.