Study on microstructure, mechanical and tribological properties of a novel high-entropy alloy based self-lubricating composite Al0.5CrFeNiV0.5-hBN

A new high-entropy alloy (HEA) based self-lubricating composite with good mechanical and tribological properties has been designed and fabricated, using Al 0.5 CrFeNiV 0.5 HEA as matrix and hexagonal boron nitride (hBN) as solid lubricant. In addition to the well dispersed hBN particles, the novel composite is consisted of (Al,Ni)-rich, (Cr,V)-rich, (Cr,Fe,V)-rich, CrVB 4 , and AlN phases. High temperature nanoindentation tests of the composite revealed its excellent thermal softening resistance, showing very good mechanical strength stability in a wide temperature range. Additionally, the composite also exhibits substantial improvements in friction reduction and anti-wear performance from RT to 700 °C. The enhanced mechanical and tribological properties are attributed to the hBN and new phases formed by reactions between hBN and Al 0.5 CrFeNiV 0.5 HEA matrix. The main wear mechanisms during sliding of the Al 0.5 CrFeNiV 0.5 -hNB composite against the Si 3 N 4 balls shift from abrasion and plastic deformation to oxidation and adhesive wear as the wear testing temperature is increased. • A new high-entropy alloy (HEA) based self-lubricating composite Al 0.5 CrFeNiV 0.5 -hBN was successfully developed. • The Al 0.5 CrFeNiV 0.5 -hBN composite exhibited good nanohardness stability in a wide temperature range. • In comparison with pure Al 0.5 CrFeNiV 0.5 HEA, the composite exhibits substantially lower friction coefficient and wear rate.