Microstructure characterization of HfNbTaTiZr High Entropy Alloy Processed in Solid State

Abstract

This work investigates the alloying degree of HfNbTaTiZr high entropy alloy in equimolar percentages from raw, high purity powder, using solid state processing, for further uses in coating work components in harsh environments like marine, geothermal or oil and gas industry. The combination of elements was chosen according their properties, tailoring the composition for the final purpose. The alloying has been performed in a planetary ball mill with stainless steel vial and balls in a protective argon atmosphere to prevent oxidation, contamination or ignition and N-heptane as a process control agent to improve the material’s behavior during welding and re-welding in mechanical alloying process. Samples were taken at regular periods of time and analyzed to check the alloying degree evolution and to establish the optimum parameters for milling, best results being obtained at a speed of 300 rpm for 180 min (effective time) providing an alloying degree over 50% was achieved.

New HfNbTaTiZr High-Entropy Alloy Coatings Produced by Electrospark Deposition with High Corrosion Resistance

“…The investigation was realized for each stage to observe the transformation occurring during HEA processing. The mechanical alloying process was widely described in a previous paper [ 21 ], where the following parameters were used: 300 RPM speed for 30 h in an argon atmosphere with 10:1 BPR and n-heptane as PCA. The process was further improved by increasing the milling time up to 60 h. The mean particle size dimension of the initial pure powders was 63 μm.…”

“…The peaks after mechanical alloying reveals a good alloying degree with the main BCC phase confirmed also in this alloy’s VEC. We previously investigated this alloy, and the alloying degree was low after 30 h of mechanical alloying [ 21 ]. However, now the XRD revealed a good alloying degree, and we could use the powder to further process and manufacture the ESD electrode.…”