Cr-rich layer at the WC/Co interface in Cr-doped WC–Co cermets: segregation or metastable carbide?

• Published in: Journal of crystal growth Vol. 270; no. 1-2; pp. 219 - 227
• Main Authors: Delanoë, A., Bacia, M., Pauty, E., Lay, S., Allibert, C.H.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.09.2004; Elsevier
• Subjects: A1. Interfaces; A1. Segregation; A3. Epitaxy; B1. Cemented carbides; B1. Chromium carbide; Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Materials science; Physics; Solubility, segregation, and mixing; phase separation; Treatment of materials and its effects on microstructure and properties; 68.55.−a; B1. Cemented carbides; 8.55.Nq; A3. Epitaxy; A1. Segregation; B1. Chromium carbide; A1. Interfaces; FCC lattices; Inorganic compounds; Nucleation; Segregation; Metastable states; Doping; Chromium additions; Cobalt; 8.55.Nq A1. Interlaces; Chemical composition; Tungsten carbides; Transition element compounds; Solubility; Binary compounds; 68.55.-a; Experimental study; Lattice parameters; Interfaces; Transmission electron microscopy; Transition elements; Sintering; Microstructure
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2004.05.101

The effect of Cr on the microstructure of WC–Co alloys after liquid-phase sintering is studied as a function of the C content of the alloy and for two Cr for Co substitution ratio. The distribution of Cr is investigated using X-ray energy dispersive spectrometry. A Cr enrichment at WC/Co interfaces is detected for both C- and W-rich alloys. The observations by high-resolution electron microscopy point out a thin face centred cubic layer at the interface between WC and Co. This layer has grown epitaxially on the surface of the WC grains with two orientation relationships depending on the WC plane. The lattice parameter mismatch is close to 0.2% for the basal plane and less than 3% for the prismatic plane of WC. The composition and crystal structure of this compound correspond to the metastable (Cr,W)C phase that is stabilized by the low energy of the WC/(Cr,W)C interface.