Influence of Impurities in Tungsten and Matrix Composition on the Tungsten-Matrix Interfacial Properties of Heavy Metal Alloys

摘要

The mechanical properties of tungsten heavy metals are strongly influenced by the quality of the starting materials, especially the powders. Powders that are too coarse result in highly porous heavy metals, regardless of the sintering conditions, as, due to insufficient distribution of the binder melt, liquid phase sintering occurs only locally. A second, although different, type of porosity is caused by traces of alkaline metals or rare earths, the pores in this case being formed during liquid phase sintering. These elements apparently promote reduction of oxide traces and Ostwald ripening of the resulting micropores. The influence of most other impurities is less pronounced but could be identified by statistical evaluation.