Berlin 2018 – scientific programme

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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 Al_xCoCrFeNi 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 Al_xCoCrFeNi (x = 0.5, 1 and 2) alloys.

Tracer diffusion in the Al_xCoCrFeNi alloys is measured between 800 ^∘C and 1100 ^∘C by applying the ⁵¹Cr, ⁵⁷Co and ⁵⁹Fe radioisotopes. As the Al content x in the Al_xCoCrFeNi 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.