Effect of W on the Mechanical Properties and Tribological Behavior of CoCrFeNiW_x Compositionally Complex Alloy

Introducing the hard second phase into soft matrix and reducing the grain size are key strategies to enhance the strength and wear performance of metallic alloys. Herein, to investigate the effect of hard second phase on the mechanical properties and tribological behavior of face-centered-cubic (FCC) CoCrFeNi compositionally complex alloy (CCA), a series of ultrafine-grained CoCrFeNiWx (x = 0, 0.3, 0.5, and 1.0) CCAs with varying W contents are fabricated. The results show that the single FCC CCA transforms to the dual phase of FCC and mu phase after addition of W. With increasing W content, the hardness and yield strength show a linear increase due to the additional solid solution strengthening and secondary phase strengthening, but the fracture strain shows an opposite trend. Dry sliding wear tests show that both coefficients of friction and wear rates decrease with the W content. The wear mode changes from abrasive wear for CoCrFeNi CCA to multiple wear modes of abrasive wear, oxidative wear, and fatigue wear for W-containing CCAs. These results suggest that adding W into the FCC CCA matrix could strengthen the FCC alloy and simultaneously improve wear performance.