Effect of Niobium on Microstructure and Properties of the CoCrFeNbxNi High Entropy Alloys

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2017,（7）
• 页码范围: 712-717
• 页数: 6页
• 语种: 英文

摘要

A series of CoCrFeNbxNi (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 CoCrFeNbxNi (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＜ 1.2).The compressive test results show that the Nb0.45 (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.