High temperature tensile behaviors of two W-free Co-Ni-Al-based γ'-strengthened superalloys at 773 K ~ 1073 K were investigated. The tensile strength and elongation of two superalloys decrease with increasing temperature. The fracture mechanism changes from dimple fracture to brittle fracture. A detailed observation of the fracture shows that the intermediate temperature embrittlement caused by decohesion of slip plane plays a significant role in reducing high temperature performance. Both superalloys reach to peak yield strength at 923 K. Occurance of yield strength anomaly (YSA) is derived from the synergistic effects of dislocation locking strengthening and dynamic strain aging strengthening. Dislocation cross-slipping hinders the dislocation migration. Dislocations' unpinning to the moving solutes increases the yield strength at 723 K ~ 973 K. A rapid weakening of grain boundaries strength decreases the yield strength at 1073 K.
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1991 M.Sc., Department
of Industrial Engineering of Forestry, Black Sea Technical University, Turkey 1988 B.Sc., Department of Industrial Engineering of
Forestry, Black Sea Technical University, Turkey
Publications (selected) Efe, FT Alma, MH, 2014. Investigating Some Physical
Properties of Composite Board, Produced from Sunflower Stalks, Designed
Horizontally, Ekoloji, 23 (90): 40-48. Alma M. H.; Acemioğlu, B. (2003): A Kinetic Study of
Sulfuric-Acid-Catalyzed Liquefaction of Wood into Phenol Chemical Engineering
Communications . 191: 969-980. Alma, M.H.; Basturk M. A.; Dıgrak M. (2003): New
Polyurethane-Type Rigid Foams From Liquified Wood Powders Journal of Materıals
Scıence Letters 22, 1225 –1228. Bektaş, I; Alma M. H.; As, N.; Gundoğan R. (2003):
Humidity as a Use Condition for Accelerated Aging of Polymers designnews.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from designnews.com Daily Mail and Mail on Sunday newspapers.