THE HARDNESS OF CERTAIN NIOBIUM-BASE ALLOYS AT ELEVATED TEMPERATURES
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO
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An investigation was made of the changes in the hardness of Nb and Nb alloys with temperature by the method of hot hardness. A series of Nb alloys were prepared from Nb 99.2, Mo 99.9, Zr 99.8, Sitechnical grade, Al 99.9 and carbon by arc fusion. The specimens were remelted several times and homogenized in a TVV-2 vacuum furnace at 1600 C for 10 hr. Hardness measurements were carried out on a VIM-1 instrument under vacuum at 20, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 C. The impressing time of the diamond pyramid was 1 min. Three impressions were made on the specimen at each temperature. The diagonal of the impression was determined on a PMT-3 instrument for measuring microhardness. It was concluded that 1 Nb, like Ni, Fe, and Co can be hardened by alloying with components which form with it solid solutions with separation of the excess phase 2 the method of hot hardness makes it possible to characterize the strength of alloys at elevated temperatures and 3 multicomponent alloys with a high hardness at 1000 C require further investigation and testing for heat resistance by the standard method.