| The uranium alloy containing 5wt％Nb, which has a high density of 17.9g/cm3, and has good corrosion resistance, along with the high strength and good ductility adjusted by heat treatment, was used extensively in technology and engineering. This work was subjected to the preparation and solidification process, mechanical property and microstructure of the U-5wt％Nb alloy.The CaO crucible was used in the induction furnace to avoid the contamination of carbon, as well as simplify the alloying procedure of U-5 wt％Nb alloy, provided ideas to preparation precedure of dystectic alloys. Within the casting of U-5wt％Nb part, the mold was prewarmed to form a temperature gradient, and the part was cooled by a controlled speed, and the well-moulded cast was obtained. As to control the casting of alloys which has a wide crystallization temperature zone, these measure could be refered especially to the controlment for casting defect such as shrink.The solidifying microstructure and the impurity of U-5 wt％Nb alloy quenched from the solid-liquid temperature after preservation were investigated by optic microscope and SEM. As the results shows, the initial solidification temperature was 1325℃, and the final solidification temperature was 1195℃. The impurities in the cast was complex in shape and type, and four type impurities were dominated with carbide and unmelted Nb in. In the solidifycation ending position or grain boundary, a mount of impurities as the C, O, S, Ca would enriched. All above works provided bases for the improvement of U-5 wt％Nb part's cast process, and can be used for the study of solidification procedure for other alloys.The mechanical property test of U-5 wt％Nb alloy exhibited that, low yield stress and higher prolongation was achieved in as-quenched samples; low temperature aging showed less effect to its strength and ductility, but more improvement exhibited in elastic modulus. After temper inα+γ1 orγregion temperature, the yield strength and elastic modulus increased, as the ductility decreased, and the microstructure changed into two phase.
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