Effect of Minor Elements on the Grain Boundary Strengthening of a Single Crystal Superalloy RR2072
Effect of carbon and boron on the grain boundary strengthening of a second generation single crystal superalloy RR2072 was investigated. Single crystal and bicrystal specimen with three kinds of tilt type misorientation angle were grown by Bridgman technique. Creep and stress rupture tests were conducted at 950oC and 1050oC. Rupture life of single crystal of the alloy modified with carbon and boron was comparable to that of the RR2072 which is free from boron and carbon. TCP phase precipitation such as sigma was suppressed in the modified alloy during thermal exposure and creep deformation. Rupture life of the modified alloy bicrystal was superior to that of the RR2072 bicrystal. M23C6 carbide formation and suppression of γ′ band growth is thought to be the role of minor elements for the grain boundary strengthening of a nickel base single crystal superalloy RR2072.
Byung Tae Ahn, Hyeongtag Jeon, Bo Young Hur, Kibae Kim and Jong Wan Park
D.H. Kim et al., "Effect of Minor Elements on the Grain Boundary Strengthening of a Single Crystal Superalloy RR2072", Solid State Phenomena, Vols. 124-126, pp. 1405-1408, 2007