Regensburg 1998 – scientific programme

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M: Metallphysik

M 21: Kristallplastizität I

M 21.3: Talk

Thursday, March 26, 1998, 10:50–11:10, H 38

RAFTING OF γ′-PRECIPITATES IN A SINGLE CRYSTAL NI-BASE SUPERALLOY UNDER MULTIAXIAL STRESS
CONDITIONS — •Muthuswamy Kamaraj, Matthias Kolbe, and Gunther Eggeler — Ruhr-Universit"at Bochum, Institut f"ur Werkstoffe, Werkstoffwissenschaft, 44780 Bochum

Nickel - based single crystal superalloys are used for manufacturing of turbine blades because of their good combination of high temperature creep strength and oxidation resistance. The microstructure of these alloys consists of a high volume fraction of coherent cuboidal L1₂ γ′- particles embedded in a f.c.c γ-matrix. During service the material is subjected to multiaxial stress and high temperature (>1000^∘C) and the morphology of γ′- particles is transformed by directional coarsening. Therefore, it is important to study the rafting phenomenon under multiaxial stress states. In the present investigation, we report the rafting of γ′- particles in the single crystal superalloy CMSX-6 above 1000^∘C using a double shear creep test technique. The coarsening of γ′- particles is characterised in different locations of the shear zones using scanning electron microscopy. We discuss the influence of bending and shear stresses on γ′- rafting.