Next-Generation Cobalt-Free Tungsten Carbide Enabled by FeNiZr Binder Alloys

Author(s):

Sean J. Fudger, Kenneth Brown, Billy C. Hornbuckle, Thomas L. Luckenbaugh, Philip E. Goins, and Kristopher A. Darling

Abstract:

Cemented tungsten carbide (WC) is widely used in cutting, machining, mining, and defense applications due to the exceptional hardness and high modulus provided by the WC phase combined with the plasticity and toughness imparted by the cobalt (Co) binder. Despite its widespread use, Co has been identified as both a strategic and critical material by the U.S. Department of the Interior and as a substance anticipated to be a human carcinogen by the U.S. Department of Health and Human Services, motivating the development of alternative binder systems that maintain the performance of conventional WC–Co materials. In this work, nanostructured FeNiZr is evaluated as a potential Co replacement due to its favorable mechanical properties and reduced health and supply-chain concerns. WC–FeNiZr composites were fabricated using both commercial press-and-sinter processing and field-assisted sintering followed by hot isostatic pressing, producing near–fully dense materials with hardness values exceeding 13.5–16.0 GPa (1377–1630 HV) and fracture toughness values up to 15 MPa·m^1/2 (10 ksi·inch^1/2). Microstructural characterization using scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy were used to investigate the structure–property relationships governing these materials. In addition, tribological wear testing was conducted to compare the performance of WC–FeNiZr composites with conventional WC–Co systems, while machine learning approaches were employed to guide materials development by enabling efficient exploration of complex, multifactorial processing–composition–property relationships.