Hard-metal body

A hard-metal body comprising a hard-metal, the hard-metal comprising tungsten carbide grains and metal binder comprising cobalt having a concentration of tungsten dissolved therein, the body comprising a surface region adjacent a surface and a core region remote from the surface, the surface region and the core region being contiguous with each other;

• the mean binder fraction of the core region being greater than that of the surface region;
• the mean carbon concentration within the binder being higher in the surface region than in the core region;
• and the mean magnetic moment of the hard-metal in the surface region being greater than that in the core region;
• the hard-metal body being substantially devoid of eta-phase and free carbon;
• and the concentration in weight percent of tungsten dissolved in the binder in the surface region being less than that in the core region, the concentration in weight percent of tungsten dissolved in the binder being determined as (16.1−σB)/0.275;
• σB being the magnetic moment of the hard-metal within a region of the hard-metal body divided by the binder weight fraction in the region, in which the mean magnetic moment of the hard-metal body in units of micro-Tesla times cubic metre per kilogram of the material is in the range from 0.131X to 0.161X within the surface region, and in the range from 0.110Y to 0.147Y within the core region, X and Y being respectively the weight percent of the cobalt within the surface and core regions;
• both X and Y being at least about 1 and at most about 50 weight percent.