Regensburg 2019 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 12: Poster session I
MM 12.33: Poster
Monday, April 1, 2019, 19:15–20:45, Poster C
invar effects in FeNiCo medium entropy alloys: from an invar treasure map to alloy design — •ziyuan rao1, dirk ponge1, fritz körmann1,2, yuji ikeda1, oldřich schneeweiss3, martin friak3, jörg neugebauer1, dierk raabe1, and zhiming li1 — 1Max-Planck-Institut für Eisenforschung, Max-Planck-Straße 1, 40237 Düsseldorf, Germany — 2Materials Science and Engineering, Delft University of Technology, 2628 CD Delft, The Netherlands — 3Institute of Physics of Materials, Academy of Sciences of the Czech Republic, v.v.i., žižkova 22, Brno CZ-616 62, Czech Republic
To facilitate the understanding and design of FeNiCo-base invar alloys characterized by low thermal expansion coefficient (TEC), we investigated the magnetic and thermal expansion behavior of an equiatomic prototype medium entropy alloy FeNiCo and a non-equiatomic (super invar) Fe63Ni32Co5 (at. %) reference alloy by means of experiments and ab initio calculations. Large spontaneous volume magnetostriction is observed in both alloys below their respective Curie temperatures. The invar effect in the non-equiatomic Fe63Ni32Co5 alloy is of step-type with nearly zero TEC over a wide temperature range (from room temperature to 120 oC) below its Curie temperature. The relationships among magnetic behavior, spontaneous volume magnetostriction and invar effects for a wider array of metallic alloys are discussed based on Masumoto*s rule and Wohlfarth*s itinerant electron theory. An invar alloy search map is constructed based on the present results and available literature data, which provides a design route for further developments of new invar alloys by tuning their magnetic properties.