Wear behavior of functionally graded cemented carbides with CoNiFeCr multi-principal-element alloy binder

Abstract

The good combination of mechanical and wear properties for cemented carbides is crucial. In this work, the wear behavior of functionally graded cemented carbide (FGCC) and non-graded cemented carbide (CC), with CoNiFeCr multi-principal-element alloy (MPEA) binder, has been investigated by performing sliding wear tests and composition characterization. The results showed that compared with CC, FGCC had higher hardness, stronger fracture toughness, better wear performance, and similar TRS. FGCCs exhibited lower wear rates (3.44 × 10^-7-6.95 × 10^-6 mm³/(N·m)) and coefficients of friction (COFs) (0.27-0.39) than CCs from RT to 600 °C due to mitigation of multiple risks caused by binder removal, fragmentation and pull-out of WC grains, high-temperature oxidation and softening. In the low-temperature wear stage, the MPEA binder underwent dynamic recrystallization (DRX) and twinning deformation before removing from the surface. The binder removal caused dislocation pile-ups and stacking faults (SFs) to form under high stress, resulting in fragmentation and pull-out of WC grains. The low-temperature wear was dominated by abrasive wear and adhesive wear, with a low wear rate and a high and unstable COF. In the high-temperature wear stage, initial pitting oxidation of WC grains generated many subgrain boundaries, reducing heat transfer and exacerbating oxidation, resulting in an oxide layer enriched with WO₃, M_xO_y, and MWO₄. High-temperature wear was dominated by oxidation wear and high-temperature softening, with a high wear rate and a low and smooth COF. The results from the present study do not only provide theoretical guidance for an understanding of the antiwear mechanism of WC-CoNiFeCr, but also a new approach for the preparation of cemented carbides with high wear resistance.