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MM: Fachverband Metall- und Materialphysik

MM 2: Topical session (Symposium MM): High entropy and compositionally complex alloys

MM 2.4: Vortrag

Montag, 1. April 2019, 11:15–11:30, H43

Nanoscale, continuous phase separation of Al-containing compositionally complex alloys via Laser Powder Bed Fusion — Nicolas J. Peter¹, •Hyo Yun Jung¹, Eric Gärtner², Volker Uhlenwinkel², Gerhard Dehm¹, and Eric A. Jägle¹ — ¹Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany — ²Leibniz IWT, Bremen, Germany

Literature shows that increasing Al-additions to the Cantor alloy transformed the initially single-phase FCC (A1) alloy to a BCC (A2 matrix/B2 precipitates) material with superior strength in casts. In contrast to such previous studies, we make use of the selective laser melting process. We investigate three different compositionally complex alloys, namely AlCoCrFeNi, AlMnCoCrFeNi and AlCu_0.5FeNiCoCr_0.75. The same microstructure is found for all three alloys using advanced electron microscopy consisting of a coherent two-phase structure with interwoven A2/B2 phases. Atom probe tomography confirms the nanoscale phase separation into Ni-Al and Fe-Cr domains. An effect of the intrinsic heat treatment can be excluded as the gas atomized powder used for selective melting already contained both phases. In addition, melt spun reference samples of AlCu_0.5FeNiCoCr_0.75 were investigated and found to adopt the same interwoven A2/B2 microstructure. Our results therefore point to a conditional spinodal decomposition process, which is currently further investigated. Finally, first results on establishing the structure-property relationships are presented.