Tailoring alloys using hot pressing and mechanical alloying

摘要

Many intermetallic compounds, such as chromium silicide, have attractive properties including high hardness, stiffness and good chemical resistance. In order to exploit these properties the hard phase is often combined with softer phases to form a multi-phase composite. In trying to improve the strength and toughness of chromum silicide, it has been necessary to not only add a second more ductile phase, but also to modify the ductile second phase individually in order to balance the properties. Non equilibrium phase mixtures can be created by combining powder metallurgy techniques with mechanical alloying, in contrast to melt processing techniques which typically produce equilibrium phase compositions and chemical inhomogeneities. Elemental powders can be mechanically alloyed to form the necessary composition for either phase, also including dispersoids in one or both phases. More rapid alloy development is possible, as well as the possibility of producing feedstock for rapid prototyping. Research on the ductile phase toughening of chromium silicide will be presented as an example of this approach to tailoring composite materials.