Manufacturing of Mo-25 Re and Mo-50 Re Alloys by Means of Powder Sintering at Medium Temperatures

Abstract

Powder mixtures of molybdenum and rhenium were sintered at various temperatures to fabricate Mo-25% Re and Mo-50% Re alloys. For this purpose, stoichiometric mixtures of the component powder metals with particle sizes of 1 to 5 μm average, were first homogenized in a planetary mill and then compacted at 300, 400, 500 and 600 MPa, to the shape of tablets and small billets for rolling to thin foils. The obtained pieces were subjected to sintering at various temperatures in the range of 1400 to 1700°C, under argon-hydrogen protecting atmosphere. The solid solution of rhenium in the molybdenum matrix was followed by means of x-ray diffraction. It was found that at all sintering temperatures rhenium was totally dissolved in theMo-25% Re alloy, while small amounts of an intermediate phase were detected in the case of the Mo-50% Re alloy, in good agreement with the corresponding phase diagram. The densification of sintered parts increased with temperature and compaction pressure up to values less than 90%. Owing to the fine particle size of the powders, the sintering temperature can be lower than those normally utilized in the refractory metals industry.