Damage tolerant anisotropic nickel base superalloy articles

摘要

Columnar grain and single crystal nickel base superalloys are heat treated to provide a damage tolerant microstructure. The microstructure contains large, irregularly shaped "barrier" gamma ' particles interspersed in an ordered array of smaller cuboidal gamma ' particles in a gamma phase matrix. The barrier particles interrupt the progression of cracks through the microstructure. The invention process includes solutioning the gamma ' phase, cooling slowly to a temperature about 50 DEG F. to 150 DEG F. (28 DEG C. to 83 DEG C.) below the gamma ' solvus temperature, further cooling at a rate of at least about 100 DEG F. (56 DEG C.) per minute to less than 1000 DEG F. (538 DEG C.), reheating to 1975 DEG F. to 2000 DEG F. (1079 DEG C. to 1093 DEG C.) and holding for about four to six hours, cooling at 100 DEG F. (56 DEG C.) per minute to less than 1000 DEG F. (538 DEG C.), and heating to 1600 DEG F. +/-25 DEG F. (871 DEG C. +/-14 DEG C.) and holding for 24 hours to 32 hours.