Metal injection molding (MIM) of heavy alloys, refractory metals, and hardmetals

Abstract: This chapter begins with an overview of the uses of heavy alloys, refractory metals, and hardmetals. The characteristics and preparation of refractory metal-based powders for metal injection molding (MIM) are discussed. Examples of binders and mixing techniques for preparing injection molding feedstock from these powders are described. Processing conditions for liquid-phase sintering MIM heavy alloys, including W–Ni–Fe and W–Ni–Cu, are described with specific emphasis on minimizing distortion while obtaining the desired properties. Solid-state and activated sintering of MIM refractory metals and alloys is reviewed with discussion of specific processing conditions for W, Re, Mo, Ta, and Nb, including the effects of alloy or oxide additions. Hardmetal compositions, primarily based on WC–Co, are reviewed and processing conditions for liquid-phase sintering are described with an emphasis on carbon control.