The effect of cooling rate on the microstructure and mechanical properties of NiCoFeCrGa high-entropy alloy

• Published in: Journal of materials science Vol. 54; no. 6; pp. 5074 - 5082
• Main Authors: Molnár, Dávid, Vida, Ádám, Huang, Shuo, Chinh, Nguyen Q.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2019; Springer; Springer Nature B.V
• Subjects: Alloy systems; Alloys; Analysis; Body centered cubic lattice; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Cooling; Cooling effects; Cooling rate; Crystallography and Scattering Methods; EBSD; Electron backscatter diffraction; Electron microscopy; Energy dispersive X ray spectroscopy; Entropy; Face centered cubic lattice; Heat treating; high entropy alloy; High entropy alloys; Materials Science; Mechanical properties; Metals; Metals (Materials); Microhardness; Microscopy; Microstructure; Nickel; Polymer Sciences; Scanning electron microscopy; Self-similarity; Solid Mechanics; Specialty metals industry; Spectroscopy; Steel Forming and Surface Engineering; Stålformning och ytteknik; X-ray spectroscopy; Electron Backscatter Diffraction (EBSD); Wedge-shaped Samples; High-entropy Alloys (HEAs); Empirical Rules; Valence Electron Concentration (VEC)
• ISSN: 0022-2461; 1573-4803; 1573-4803
• DOI: 10.1007/s10853-018-03196-8

The effect of cooling rate on the microstructure and mechanical properties of equimolar NiCoFeCrGa high-entropy alloy (HEA) was studied by scanning electron microscopy, energy-dispersive X-ray spectroscopy and electron backscatter diffraction (EBSD), as well as by microhardness tests. Experimental results show that the cooling rate has a crucial impact on the developing microstructure which has a mixture of two—FCC and BCC—phases, leading to a self-similarity of the solidified structure formed in the sample. Furthermore, the cooling rate influences both the composition of the two phase-components and the ratio of their volume fractions, determining the mechanical properties of the sample. The present results confirm the grouping of Co, Fe and Cr in the FCC phase and that of Ni and Ga in BCC phase in the NiCoFeCrGa high-entropy alloy system. An empirical rule is suggested to predict how the phase-components can be expected in this complex high-entropy alloy.