Formation of W-Re Solid Solution by Mechanical Alloying

Progress of mechanical alloying (MA) during milling of W with Re, in a SPEX Mill was monitored by x-ray diffraction, scanning electron microscopy and transmission electron microscopy. XRD patterns showed continuous decrease in the intensity of Re peaks with increasing MA time. However the Re peaks continued to be present even after 18 ks of milling. 36 kiloseconds of milling showed complete dissolution of Re, as observed by the absence of Re peaks in association with W peak shift in accordance with the dissolution of Re in W. Chemical homogeneity and extensive reduction in particle size of the alloy could be established by microstructural and chemical analysis using SEM and TEM. Isothermal heat treatment of the mechanically alloyed sample at 1700 K for 4 hours did not show any decomposition of the alloy. A similar heat treatment of the blended elemental powder showed the formation of metastable phase formation, possibly at the boundary of dissimilar powder particles. After pressing and sintering of pellets, tests revealed some amount of alloy contamination by iron through milling.