Abstract: A specific composition range and process sequence are described for the production of single crystal superalloy articles which have an exceptional combination of high temperature mechanical properties and resistance to oxidation and hot corrosion. The nominal composition is 6% Ta, 9% Cr, 5% Co, 1% Ti, 1% Mo, 7% W, 5.5% Al, 0.15% Hf balance essentially nickel. Material of this composition is cast and solidifed in single crystal form and heat treated to produce an optimum microstructure.

Abstract: An article of manufacture exhibiting cyclic oxidation-hot corrosion resistant properties comprising a non-eutectic nickel-base superalloy consisting essentially of, on a weight basis, 1-9% Re, 0-2% Ti, at least 2% Al, 3-12% Cr, 1-5.9% Ta, 0-0.5% C, 2-12% Co, 2-10% W, less than 1% V, 2-10% Mo, 0-5% Cb, 0-3% Hf, 0-1.5% Zr and 0-0.20% B, the balance being essentially Ni and incidental impurities. Especially preferred are articles of manufacture in the form of a unidirectionally solidified anisotropic metallic body of the above alloy composition.

Abstract: An improved method of producing a nickel-base single crystal superalloy cast article having a refined gamma prime phase disposed in a gamma phase matrix includes casting the single crystal article with a coarse gamma prime phase disposed in a gamma phase matrix. A stress concentration may be formed in a portion of the article. This stress concentration may be of sufficient severity to cause recrystallization upon heating of the single crystal article to a solution heat treatment temperature at which the gamma prime phase can go into solid solution in the gamma phase. To prevent recrystallization from occurring, the severity of the stress concentration is reduced by heating the single crystal article to a recovery temperature which is below the temperature at which recrystallization occurs. Thereafter, the article is solution heat treated to cause the gamma prime phase to go into solid solution with the gamma phase.

Abstract: An alloy composition coasting scheme and specific heat treatment process are described for the production of directionally solidified single crystal articles which have exceptional properties. The alloy is based on the Ni-Al-Mo system, preferably with additions of Ta. The process for producing the article inclused directional solidification at a high rate to produce a fine dendritic microstructure. A combined homogenizing and solution treatment is performed to provide a unique chemically homogeneous single phase microstructure. This homogeneous article is rapidly quenched and then aged at an intermediate temperature to develop a controlled uniform distribution of fine gamma prime phase particles.