Microstructural Investigations of Rapidly Solidified Cu-Nb Alloy Powders Producedby Inert Gas Atomization

摘要

This study presents a metallographic technique which enables the microstructuralexamination of the cross-sections of individual, fine-scale (10-75 um) powder particles. The technique was developed to permit characterization of the 'as-solidified' features of Cu-based powders produced by high pressure inert gas atomization in order to relate the microstructures to processing history. In order to perform the necessary microscopy to elucidate the microstructural features, a metallographic technique was developed to permit characterization of the 'as-atomized' microstructures within the individual powder particles. This technique involved classifying, mounting, and polishing through the diameters of individual powder particles and then using an 'attack etch' to remove some of the copper matrix. This enabled characterization of the niobium-rich second phase. Secondary electron imaging on a scanning electron microscope provided the necessary resolution to characterize the second phase morphologies as a function powder-particle size, ultimately relating the microstructures to processing conditions.