Magnetic Properties of the Cobalt Matrix in WC-Co Compacts
1983; Elsevier BV; Linguagem: Inglês
10.1016/b978-0-08-029358-5.50041-0
AutoresHaydée Le Roux, D.S. McLachlan,
Tópico(s)Metallic Glasses and Amorphous Alloys
ResumoA series of sintered WC-Co hardmetals containing 3 to 25 wt% Co and a presintered (i.e., compressed but unsintered) hardmetal containing 8 wt% Co were studied by measuring their magnetic properties in a Foner magnetometer. Internal demagnetising factors (Nif) of the hardmetals were obtained from inverse slopes of anhysteretic magnetisation curves after correcting for external demagnetising factors. The very small magnitudes of Nif of sintered materials confirm that Co is not present as discrete particles but as a continuous interlinked network of ferromagnetic thin films resembling a ferromagnetic sponge. The decrease in coercivity (Hc) occurring on densification is ascribed to magnetostatic interactions between newly bonded Co films. Whereas the Hc of the continuous matrix depends on the mean Co layer thickness the remanence ratios (jr), after correction for an external demagnetising factor, depend on the thickness of the thickest Co films present. Relationships between Co content and/or WC grain size and some magnetic properties (Nif, Hc, and jr) are established. Some mechanical properties are considered.
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