Fine-grained, high-density (97%+ of theoretical density [TD]), 80 tungsten-20 copper weight-percent (80W-20Cu [58W-42Cu atomic-percent]) composites have been prepared using nonconventional alloying techniques. The W and Cu precursor powders were combined by high-energy ball milling in air. A second set of W+Cu mixtures was prepared in hexane to reduce contamination of the powders. The mechanically alloyed W+Cu powder mixtures were then coldpressed into green compacts and sintered at 1,250 °C. The effects of varying the milling medium and milling time were examined with density measurements. Longer milling increased product densities with a concomitant order-of-magnitude decrease in grain size; air was found to be a more effective medium than hexane. Residual impurities were identified with energy-dispersive x-ray spectroscopy (EDS), and their effects on sample properties were evaluated with microhardness measurements. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses demonstrated that the as-milled W-Cu alloy structures were metastable, decomposing into the starting W and Cu components upon heating at or above 450 °C. AcknowledgmentsThe authors gratefully note the contributions of Mr. Daniel Snoha for his careful review of the manuscript and his comments regarding the deterrnination and sources of baU-milling-induced lattice strain. m INTENTIONALLY LEFT BLANK. IV
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