Effects of the sp element additions on the microstructure and mechanical properties of NiCoFeCr based high entropy alloys

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 669; pp. 14 - 19
• Main Authors: Vida, Adam, Varga, Lajos K., Chinh, Nguyen Quang, Molnar, David, Huang, Shuo, Vitos, Levente
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 04-07-2016
• Subjects: Alloys; Body centered cubic lattice; Entropy; Face centered cubic lattice; Gallium base alloys; High entropy alloys; High strength; Mechanical properties; Microstructure; Multiphase materials; Scanning electron microscopy; High entropy alloys; Mechanical properties; High strength; Multiphase materials
• ISSN: 0921-5093; 1873-4936; 1873-4936
• DOI: 10.1016/j.msea.2016.05.082

The effects of the sp (Al, Ga, Ge, Sn) element additions on the microstructure and mechanical properties of equimolar NiCoFeCr High Entropy Alloys (HEAs) are investigated. The results of X-ray diffraction measurements combined with scanning electron microscopy SEM investigations, as well as the results of nanoindentation test revealed that while the structure of the basic alloy is full FCC, the addition of sp elements has changed it to a multiphase containing both FCC and BCC components, but in different scales. Accordingly, the addition of sp elements strongly increases the strength of the basic state, especially in the case of alloys where the BCC phase is dominant in the microstructure.
The physical properties as the Young’s- and shear moduli of the investigated HEAs were also determined using ultrasound methods. The correlation between these two moduli suggests a general relationship for metallic alloys.