Solid-particle erosion of a dual-phase AlCoFeNi2 high-entropy alloy

Material removal due to solid-particle erosion results in mechanical failure of equipment and tremendous financial impact. To decrease the removal, materials with a good combination of high hardness and ductility are highly desirable. Dual-phase high-entropy alloys (HEAs) have the potential for impact resistance and have thus attracted attention from researchers. However, there is a lack of knowledge on phase-specific microstructural evolution under repeated particle impacts. In this study, an FCC (face-centred cubic) + B2 dual-phase AlCoFeNi2 HEA was fabricated, and its erosion resistance was tested under a particle velocity range of 97–230 m/s and incident angle range of 20 °-90 ° using nominally 50 μ m angular aluminum oxide particles. 316 stainless steel (SS) was tested under the same conditions as a benchmark. Characterization tools including an electron backscatter diffraction technique were applied to assess the microstructural evolution of the eroded surfaces and subsurface damage. The dual-phase HEA exhibited an approximately 10% lower erosion rate at oblique incidence (<40 °) than 316SS. The enhanced erosion resistance of the HEA was associated with the hard B2 phase that strengthened the AlCoFeNi2 and protected the matrix from cutting erosion while the soft FCC phase served as a plastic deformation carrier. Dynamic recrystallization with refined grains beneath the eroded surface was observed in the FCC phase after the erosion test. This study not only revealed the phase-specific microstructural evolution during erosion but also indicates that dual-phase HEAs are promising for use in erosive conditions.