Dispersion aoooyed hard metal composites and method for producing same

摘要

A method for forming a sintered hard metal composite is provided in which unsintered nodules of a pre-blended hard metal powder of a first grade are uniformly dispersed into unsintered nodules of a pre-blended hard metal composite of a second grade. The pre-blended hard metal powders form a composite powder blend which is subsequently pressed and sintered to form the dispersion alloyed hard metal composite. A sufficient amount of pressing lubricant is provided to one of the pre-blended hard metal powders so that each of the hard metal powders shrinks at approximately the same rate relative to the application of pressure during the compacting process. The pressing lubricant is added to that hard metal powder which shrinks more during sintering. By providing uniform shrinkage of the constituent powder grades, migration of the binder from one constituent grade to the other constituent grade is minimized, thereby allowing the composite powder blend to achieve superior properties because each of the constituent grades maintains its own integrity. In addition, the uniform shrinkage of the constituent powders prevents irregular surface conditions of the "as sintered" surface.