Berlin 2005 – wissenschaftliches Programm
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M: Metallphysik
M 21: Intermetallische Phasen II
M 21.1: Vortrag
Samstag, 5. März 2005, 11:00–11:15, TU H2038
Microstructural characterization of Inconel 706 alloy — •V. Kindrachuk1, N. Wanderka1, J. Banhart1, D. Del. Genovese2, and J. Rösler2 — 1Hahn-Meitner-Institut Berlin, Glienicker Str. 100, 14109 Berlin, Germany — 2Technical University Braunschweig, D-38106 Braunschweig, Germany
Inconel 706 is a wrought Ni-Fe base superalloy which is used for applications at service temperatures up to 600∘C. It develops its good mechanical properties by precipitation of intermetallic phases γ’ (L12 structure) and γ” (DO22 structure) in the austenitic γ matrix. Microstructure evolution was studied after ageing times of 750 h and 5000 h at 750∘C. Characterization of the precipitates and of the matrix was carried out by three-dimensional atom probe tomography and by transmission electron microscopy. The modified stabilization treatment produces individual γ’ and γ” precipitates and γ’-γ” co-precipitates with average sizes of about 20 nm which are oriented parallel to the <001> lattice direction of the γ matrix. There were also observed much bigger individual γ” precipitates with sizes above 50 nm. In addition η precipitates forming at the grain boundaries are detected. The matrix volume fraction after MST is 89 %. During heat treatment at 750∘C the small precipitates growth first and are then transformed to η phase. The γ”-phase growths into needles of about 500 nm size. After 5000 h of ageing only one type of precipitates remains, namely η plates embedded into the matrix. The matrix is more enriched in Ni and depleted in Fe as compared with the preceding treatment. The volume fraction of the matrix is close to 93 %.