Processing and characterization of super strong and wear resistant Al–5Cu-(0-20 vol%)ZrB2 composites

Abstract

The present work explores the possibility of improving mechanical and wear properties of Al-5wt.%Cu alloy. A systematic investigation was carried out to understand the effect of hot press parameters and ZrB2 content (0, 5, 10, 20 vol %) on the Al–Cu alloy densification, microstructure and properties. The relative density of Al – 5 wt% Cu was enhanced from 97.07 to 99.69% with the addition of 5 vol% ZrB2 and further addition of ZrB2 lowered it's density (97%). The hardness of the Al–5Cu alloy increased significantly from 1.23 to 3.42 GPa with increase addition of ZrB2 reinforcement. Also the compressive yield strength of the Al–5Cu–ZrB2 composites increased by 217% (359–780 MPa). The combination of precipitation hardening and dispersion strengthening were attributed to such outstanding improvement in hardness and strength of Al–Cu–ZrB2 composites. The COF of Al composites varied narrowly between 0.32 and 0.40 and the wear rate decreased significantly in the range of 94.3–27.1 × 10−6 mm3/Nm after sliding against steel disc. The wear mechanisms of Al–5Cu transformed from predominantly abrasion to adhesion along with tribooxidation with the ZrB2 reinforcement. Overall, such high hardness, compression strength and low wear rate values were good combination of properties achieved for this class of materials.