Dresden 2009 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 31: Topical Session High Temperature Materials II
MM 31.1: Topical Talk
Mittwoch, 25. März 2009, 14:45–15:15, IFW A
Single-crystal nickel-base-superalloys: Correlation between high temperature properties and microstructure — •Thomas Link1, Alexander Epishin1, Udo Brückner2, and Bernard Fedelich2 — 1Technical university Berlin, Germany — 2Federal institute of material reasearch and testing Berlin, Germany
Nickel base-superalloys have a two phase microstructure: a disordered matrix hardened by 70 vol% of ordered precipitates. The strength depends on the properties of both phases but also on their morphology and on the condition of the interface. Dendritic solidification results in dendritic stresses, the different lattice spacings of both phases in coherency stresses. The morphology is described quantitatively and the stresses measured by X-ray diffraction. During high temperature creep deformation the morphology of the ordered phase transforms from cuboids to plates, the coherency stresses relax by interfacial dislocation networks and vacancy generation results in polyedrical pores. These processes are analysed by X-ray-diffraction, SEM, TEM and synchrotron X-ray tomography. Primary, secondary and tertiary creep are analysed by image analysis, TEM and molecular dynamics. Description of the plastic deformation needs microstructurally based models, which consider the evolution of the microstructure during service. A method, to characterise the relevant microstructural parameters is presented. The results of microstructurally based modelling are shown and a brief outlook on material development is given.