Tribological behavior of boronized Fe40Mn20Cr20Ni20 high-entropy alloys in high temperature

Abstract

Boronization can improve the wear resistance of high-entropy alloys (HEAs). However, the tribological tests on boronized HEAs were generally carried out at room temperature. In fact, materials are often applied in high temperature. Therefore, it is essential to investigate the effect of boronization on the tribological properties and mechanism of HEAs in high temperature. In present work, the hot-rolled Fe40Mn20Cr20Ni20 HEAs were boronized by the pack cementation method at 900 °C for 6 h. The tribological tests of the alloys before and after boronization were conducted in 20–600 °C. The results showed that the boronized alloys showed higher wear resistance at 20–600 °C, whose average coefficients of friction and wear rate were lower than those of hot-rolled alloys. At 20–200 °C, the main wear mechanisms of the hot-rolled alloys were abrasive and adhesive wears; while the main wear mechanism of the boronized alloys was polishing effect. At 300–600 °C, the main wear mechanisms of the alloys before and after boronization were oxidation and abrasive wear. The wear rate was reduced by the B2O3 produced on the surface of the boronized layer during wear and the good thermal stability of the boronized layer, which indicated that boronization improved the wear resistance of HEAs in high temperature.