AlxCrFeCoNi High-Entropy Alloys: Surface Modification by Electron Beam Bead-on-Plate Melting

• Published in: Metallography, microstructure, and analysis microstructure, and analysis, 2016-06, Vol.5 (3), p.229-240
• Main Authors: Nahmany, M., Hooper, Z., Stern, A., Geanta, V., Voiculescu, I.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Materials Science; Metallic Materials; Nanotechnology; Structural Materials; Surfaces and Interfaces; Technical Article; Thin Films
• ISSN: 2192-9262; 2192-9270
• DOI: 10.1007/s13632-016-0276-y

Two five-component Al x CrFeCoNi high-entropy alloys, x -0.6 and 0.8, were prepared by vacuum arc-melting. Electron beam surface re-melting was employed to modify the surface properties of the two high-entropy alloys. The effects of electron beam surface re-melting on the structure and mechanical properties of the alloys were investigated using scanning electron microscopy and the Vickers hardness test. Regions of Al 0.6 CrFeCoNi (P3 alloy) subjected to multi-pass electron beam surface re-melting showed an average value of 374 HV, an increase of 28% when compared to base metal values, while Al 0.8 CrFeCoNi (P2 alloy) welds exhibited a much higher increase to 530 HV, corresponding to a 34% increase relative to the values obtained with the base metals. In the P2 alloy subjected to multi-pass surface re-melting, significant temper softening caused by overlapping tracks was detected, in contrast to the hardening of the surface induced by a single-pass. It is noteworthy that the significant increase in hardness realized in the P2 multi-pass fusion zones resulted in a microstructure with a high tendency to crack. The increased hardness of that region subjected to electron beam surface re-melting for both alloys is likely associated with a superposition of several factors related to the high cooling rates of solidification in the electron beam re-melted areas.