〈1 0 0〉 Dislocations in nickel-base superalloys: Formation and role in creep deformation

✍ Scribed by T. Link; A. Epishin; M. Klaus; U. Brückner; A. Reznicek

• Book ID: 104061062
• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 824 KB
• Volume: 405
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/j.msea.2005.06.001

✦ Synopsis

a 1 0 0 Dislocations are observed in nickel-base superalloys after creep deformation at high temperatures and low stresses. They are formed in the ␥/␥ interfaces by a three step mechanism. First, primary dislocations with Burgers vector a/2 1 0 1 and 60 • character are left behind in the interfaces when dislocation loops glide through the ␥ channels. The 60 • dislocations move into edge orientation and react forming secondary dislocations a/2 1 1 0 . In the third step, new primary dislocations are knit into the already existing meshes of primary and secondary dislocations, which results in hexagonal misfit dislocation networks consisting of secondary dislocations a/2 1 1 0 and tertiary dislocations a 1 0 0 , both of edge type. This self-organisation process is explained by dislocation theory and crystallography.

Creep deformation accelerates when the a 1 0 0 interfacial dislocations enter the ␥ phase. During their climb towards the opposite interface, they attain a characteristic rectangular shape. This shape and the importance of the a 1 0 0 super dislocations for creep deformation are discussed.