ON THE DIAGRAMS OF STATE OF THE SYSTEM CHROMIUM-NIOBIUM

Molten alloys of chromium and niobium were produced in a high-frequency furnace under a protective argon atmosphere from powders of electrolytic chromium and niobium with particle sizes from 1 to 5 V. The resulting alloys were examined by thermal, metallographic, and x-ray analysis. It was found that in the chromium -niobium systemn only one intermetallic compound NbCr/sub 2/ is formed. It has a face-centered cubic lattice. The intermetallic compound forms eutectics with chromium-base and niobium-base solid solutions. The temaperature of eutectoid crystallization of the intermetallic compound with the cbromium-base solid solution is 1660 deg C (with a niobium content of 31 wt. %). The second eutectic point is at 1710 deg C at a niobium content of 66 wt. %. Primary solid solutions with a niobium base and a chromium base are formed. The solubility or niobium in chromium at 1350 deg C is about 3 wt. %. Long duration annealing at 1350 deg C coarsens the components of the eutectic, and after 100 hours the structure does not have a eutectoid character. Alloys of chromium with niobiom can be obtained by sintering inside a protective atmosphere at 1550 deg C. Complete recrystallization occurs, and an equllibrium state is reachedmore » by sintering for 2 to 5 hours at 1550 deg C. (J.S.R.)« less