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MM: Fachverband Metall- und Materialphysik

MM 34: Poster Session

MM 34.38: Poster

Tuesday, April 1, 2014, 18:00–20:00, P4

Combined experimental and theoretical study showing D1_a-type local order in Ni-Re — •Sascha B. Maisel¹, Nils Schindzielorz¹, Alessandro Mottura², Roger Reed³, and Stefan Müller¹ — ¹Institute of Advanced Ceramics, TUHH, 21073 Hamburg, Deutschland — ²School of Metallurgy and Materials, University of Birmingham, B15 2TT Edgbaston, United Kingdom — ³Department of Engineering Science, University of Oxford, OX1 3PJ Oxford, United Kingdom

Since the 1980s rhenium has been used as an addition to nickel-based high-temperature superalloys, since even small amounts of rhenium have a dramatic effect on creep resistance. However, the mechanisms behind this so-called rhenium-effect are still ill-understood. Using both experimental and theoretical methods, we show that the currently known phase diagram is inaccurate, and neglects a stoichiometric compound at 20 at.% Re Ni₄Re. This is expected to affect the microstructure of Ni-Re alloys, with important ramifications for Ni-based superalloys. The Ni₄Re compound is shown to be stable by means of quantum mechanical high-throughput calculations at 0K, aided by the cluster-expansion methods. Monte Carlo simulations show that it is thermally persistent up to 1100 K when considering configurational entropy. The existence of this compound was experimentally confirmed using extended x-ray absorption fine spectroscopy on a Ni_.97Re_.03 alloy.