Surface strengthening in Al0.25CoCrFeNi high-entropy alloy by boronizing

The boronized layer was prepared on the Al0.25CoCrFeNi high-entropy alloy (HEAs) by solid-boronizing method. A 50 μm-thickness boronized layer with the phases of (Ni,Co,Fe)2B and CrB has been prepared for holding 9 h at 900 °C. Remarkably, the Vickers microhardness of the boronized sample surface approximately approaches 1136 HV, which was 6.0 times of that in the unboronized condition. Surprisingly, the boronized Al0.25CoCrFeNi alloys have...