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The effect of refractory elements on the hot corrosion resistance of nickel-base superalloys

Thesis/Dissertation ·
OSTI ID:5180328
The superalloy B 1900, an alumina former, is known to possess reasonable oxidation resistance but less adequate resistance to hot corrosion. Superalloys IN 738 and U 710, chromia formers, are know to possess oxidation and corrosion resistance. Experimental alloys based on these existing superalloys are designed by mutually substituting the refractory elements Mo, W, Nb and Ta. The effects of these substitutions were tested for hot corrosion resistance. The experiments were carried out at 800, 900 and 1000{degree}C and activation energies were determined from the rate constants in the different regimes. Consistent with previous results, U 710 is the most hot corrosion-resistant standard alloy, ranked second is IN 738, and lastly is B 1900. Within the entire series of alloys, the U 710 based alloys are the most hot corrosion resistant exhibiting only the initial regime. The B 1900 based alloys with only Ta or Nb (no Mo) are the next best showing only up to accelerated attack. The IN 738 alloys rank third. Within these derivative alloys, the alloys without Nb are the best, exhibiting the smallest accelerated attack and the longest initial regime. The B 1900 based alloys containing Mo are the worst of the entire series. Within these substitutions, the alloys with Ta are the best. The alloys with Mo and Nb, and with just Mo are nearly equivalent, being the least corrosion resistant of all the alloys tested.
Research Organization:
Columbia Univ., New York, NY (USA)
OSTI ID:
5180328
Country of Publication:
United States
Language:
English