Publications

Precipitation Hardenable High Entropy Alloy for Tooling Applications

Stryzhyboroda, O. and Hecht, U. and Witusiewicz, V.T. and Laplanche, G. and Asabre, A. and Wilms, M.B. and Weisheit, A.

MRS ADVANCES
Volume: 4 Pages: 1427-1433
DOI: 10.1557/adv.2019.146
Published: 2019

Abstract
We present a high entropy alloy (HEA) from the system Al-Co-Cr-Fe-Ni with small additions of W, Mo, Si and C which was designed to allow for precipitation hardening by annealing in the temperature range from 600 to 900°C. The alloy development was supported by thermodynamic computations using ThermoCalc software and the specimens were produced by arc melting. The microstructure of one selected sample in as-cast and annealed conditions was analysed using SEM/EDS, SEM/EBSD and TEM. The as-cast microstructure consists of spinodally decomposed BCC dendrites enveloped by FCC+Cr 23 C 6 eutectic. Upon annealing at 700°C for 24 h nanoscale precipitates form within the spinodal BCC as well as from FCC. Precipitation is exquisitely uniform leading to an increase in microhardness from 415 HV0.5 in the as-cast state to 560 HV0.5 after annealing. We investigated coarsening of this microstructure using varying holding time for a constant temperature of 700°C. The microstructure evolution during coarsening and the corresponding mechanical properties obtained from instrumented indentation experiments are presented in this work. © Materials Research Society 2019.

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