Regensburg 2004 – wissenschaftliches Programm

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M: Metallphysik

M 15: Phasenumwandlungen III

M 15.1: Vortrag

Dienstag, 9. März 2004, 11:45–12:00, H16

Temperature dependence of lattice misfit in a creep deformed single crystal superalloy using synchrotron X-radiation — •Weiye Chen¹, Nora Darowski², Ivo Zizak², Gerhard Schumacher², Nelia Wanderka², Hellmuth Klingelhoeffer³, and Wolfgang Neumann¹ — ¹Humboldt-Universitaet zu Berlin, Institut fuer Physik — ²Hahn-Meitner-Institut Berlin, Bereich Strukturforschung — ³Bundesanstalt fuer Materialforschung und -pruefung Berlin

At high temperatures the application of an external load can lead to directional growth (gamma prime rafting) of gamma prime precipitates in single crystal superalloys. The lattice misfit between the gamma prime precipitates and the gamma matrix is one of the parameters which determine the kinetics and morphology of the gamma prime rafts. In the present study the gamma/gamma prime lattice mismatch in specimens of single crystal superalloy SC16 creep deformed at 1223 K and 150 MPa to a creep strain of 0.5 means of X-ray diffraction using synchrotron radiation. The measurements have been performed between room temperature and 1173 K in the both directions parallel and perpendicular to the [001] load axis. At room temperature the gamma/gamma prime lattice mismatch measured on the (002) reflection has a positive sign and is larger compared to the mismatch in the non-deformed specimen, while the mismatch measured on the (200) reflection is slightly negative and its value is smaller than that of the non-deformed specimen. In both directions the gamma/gamma prime lattice mismatch decreases with increasing temperature.