Experimental study of the mechanics of fracture in WC-Co alloys

Tungsten-carbide cobalt alloys in the range of technically relevant compositions an microstructures were fractured under controlled conditions. Stable and unstable crack propagation are shown to be equivalent with respect to crack geometry and energy release rates. Based on microscopic observations and on measurements using SEM micrographs, the nature of the process zone, the maximum extension of plastic deformation, the types of crack paths, and the area fractions of these crack paths are determined. The results, which are in partial disagreement with earlier work, provide the basis for the qualitative understanding and the quantitative description of fracture processes in composites combining a ductile phase embedded in a brittle matrix.

[1]  I. Joffe,et al.  Magnetic properties of CoW alloys in relation to sintered WCCO compacts , 1973 .

[2]  B. Roebuck,et al.  Fracture topography of WC-Co hardmetals , 1981 .

[3]  J. Chermant,et al.  Fracture toughness and fracture of WC-Co composites , 1976 .

[4]  V. Krstić,et al.  Toughening in WC–Co composites , 1985 .

[5]  S. H. Goods,et al.  Overview No. 1: The nucleation of cavities by plastic deformation , 1979 .

[6]  Hellmut F. Fischmeister,et al.  Conference Key Note Paper Development and Present Status of the Science and Technology of Hard Materials , 1983 .

[7]  M. J. Murray.  Fracture of WC-Co alloys: an example of spatially constrained crack tip opening displacement , 1977, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[8]  H. Wilsdorf.  The ductile fracture of metals: A microstructural viewpoint , 1983 .

[9]  M. Coster,et al.  Utilisation de la métallographie quantitative et de la stéréologie à l'etude des matériaux composites. II. Application à l'etude de la rupture d'eprouvettes de flexion en WC-Co. , 1976 .

[10]  J. A. Peck,et al.  Quantitative fractography of WC-Co cermets by Auger spectroscopy , 1981 .

[11]  J. B. Sande,et al.  Room temperature strengthening mechanisms in a Co-Cr-Mo-C alloy , 1982 .

[12]  Yoshio Fujiwara,et al.  A systematic investigation of elastic moduli of Wc-Co alloys , 1970 .

[13]  A. Gysler,et al.  Deformation behavior of age-hardened Ti-Mo alloys , 1974 .

[14]  J. Chermant,et al.  Utilisation de la métallographie quantitative et de la stéréologie à l'etude des matériaux composites—I. Etude critique des méthodes. Application à la fractographie quantitative , 1975 .

[15]  J. Gurland,et al.  The fracture toughness of WCCo alloys measured on single-edge notched beam specimens precracked by electron discharge machining , 1978 .

[16]  J. Gurland,et al.  The fracture toughness of WC-Co two-phase alloys—A preliminary model , 1980 .