Creep properties of different γ′-strengthened Co-base superalloys

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:550

Article

Bauer, A.¹  Neumeier, S.¹  Pyczak, F.²  Singer, R. F.³  Goeken, M.¹ 

[1] Univ Erlangen Nurnberg, Dept Mat Sci & Engn, Inst Gen Mat Properties, D-91058 Erlangen, Germany

[2] Ctr Mat & Coastal Res, Helmholtz Zentrum Geesthacht, D-21502 Geesthacht, Germany

[3] Univ Erlangen Nurnberg, Dept Mat Sci & Engn, Inst Sci & Technol Met, D-91058 Erlangen, Germany

关键词: Superalloy;    Cobalt;    Boron;    Grain boundary strengthening;    Creep;   

DOI  :  10.1016/j.msea.2012.04.083

来源: Elsevier

【 摘 要 】

The influence of various alloying elements on the creep properties of polycrystalline Co-base superalloys hardened by a ternary L1(2) compound, Co-3(Al,W) (gamma'-phase), was investigated. A Ti containing quaternary alloy shows creep strength similar to Ni-base superalloys IN100 and IN713C at 850 degrees C and strongly superior to conventional Co-base superalloys as Haynes188. The activation energy for creep between 850 and 950 degrees C is similar to the polycrystalline Ni-base superalloy IN100 in the same temperature range. Strengthening of the grain boundaries by third phase precipitates was found to be crucial for the mechanical properties. This can be achieved either by precipitation of borides or by additional intermetallic phases which precipitate due to oversaturation. During compressive creep at 850 degrees C only a slight tendency for directional coarsening occurs, while at 950 degrees C distinct gamma/gamma'-rafts perpendicular to the external compressive stress axis are formed which indicate a positive lattice misfit even at 950 degrees C. (C) 2012 Elsevier B.V. All rights reserved.

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