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MM: Fachverband Metall- und Materialphysik
MM 68: Transport (Diffusion, conductivity, heat)
MM 68.2: Talk
Thursday, March 15, 2018, 17:45–18:00, TC 010
Volume diffusion in high-entropy AlxCoCrFeNi alloys — •Josua Kottke1, Simon Trubel1, Daniel Gaertner1, Louis J. Santodonato2, Peter K. Liaw2, Sergiy V. Divinski1, and Gerhard Wilde1 — 1Institute of Materials Physics, University of Münster, Münster, Germany — 2Department of Materials Science and Engineering, The University of Tennessee, Knoxville, USA
High-entropy alloys (HEAs), i.e. multicomponent alloys with a large number of constituting elements in equiatomic or nearly equiatomic composition, attract an increased attention as potential structural materials due to their favorable mechanical and physical properties, especially at elevated temperatures. Hereby, we contribute to a debate about hypothetical sluggish diffusion phenomena in HEAs by investigating self-diffusion in AlxCoCrFeNi (x = 0.5, 1 and 2) alloys.
Tracer diffusion in the AlxCoCrFeNi alloys is measured between 800 ∘C and 1100 ∘C by applying the 51Cr, 57Co and 59Fe radioisotopes. As the Al content x in the AlxCoCrFeNi alloys is increased, a two-phase FCC+BCC microstructure replaces the single phase FCC one at x<0.3 and the material becomes single phased BCC at x=2. A careful microstructure examination using XRD, SEM and EBSD analysis allowed quantifying the measured diffusion profiles in terms of two separate contributions to long-range diffusion in FCC and BCC phases. The results indicate that the number of alloying elements in HEAs affects diffusion in FCC or BCC HEAs differently.