1. Effect of Niobium on Microstructure and Properties of the CoCrFeNb x Ni High Entropy Alloys
- Author
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Lu Yiping, Qiao Dongxu, Jiang Hui, Cao Zhiqiang, Jiang Li, Wang Tongmin, and Ting-ju Li
- Subjects
010302 applied physics ,Materials science ,Polymers and Plastics ,Mechanical Engineering ,High entropy alloys ,Alloy ,Metallurgy ,Metals and Alloys ,02 engineering and technology ,engineering.material ,Laves phase ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,Mechanics of Materials ,0103 physical sciences ,Vickers hardness test ,Materials Chemistry ,Ceramics and Composites ,engineering ,0210 nano-technology ,Ductility ,Eutectic system ,Solid solution - Abstract
A series of CoCrFeNb x Ni ( x values in molar ratio, x = 0, 0.25, 0.45, 0.5, 0.75, 1.0 and 1.2) high entropy alloys (HEAs) was prepared to investigate the alloying effect of Nb on the microstructures and mechanical properties. The results indicate that the prepared CoCrFeNb x Ni ( x > 0) HEAs consist of a simple FCC solid solution phase and a Laves phase. The microstructures of the alloys change from an initial single-phase FCC solid solution structure ( x = 0) to a hypoeutectic microstructure ( x = 0.25), then to a full eutectic microstructure ( x = 0.45) and finally to a hypereutectic microstructure (0.5 x x = 0.45) alloy with a full eutectic microstructure possesses the highest compressive fracture strength of 2558 MPa and a fracture strain of 27.9%. The CoCrFeNi alloy exhibits an excellent compressive ductility, which can reach 50% height reduction without fracture. The Nb0.25 alloy with a hypoeutectic structure exhibits a larger plastic strain of 34.8%. With the increase of Nb content, increased hard/brittle Laves phase leads to a decrease of the plasticity and increases of the Vickers hardness and the wear resistance. The wear mass loss, width and depth of wear scar of the Nb1.2 ( x = 1.2) alloy with a hypereutectic structure are the lowest among all alloy systems, indicating that the wear resistance of the Nb1.2 alloy is the best one.
- Published
- 2017