Study on the Fatigue Behavior of equiatomic CoCrFeMnNi High Entropy Alloy by in-situ Neutron Diffraction Investigation

• Main Authors: Sui, Tsung-Ruei, 隋宗叡
• Other Authors: Huang, E-Wen
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/bzhxja

碩士 === 國立交通大學 === 材料科學與工程學系所 === 105 === Equiatomic CoCrFeMnNi high entropy alloy(HEA) is single phase FCC material under room temperature and pressure, also known as the material with highest toughness. This research aims to investigate a five-element HEA CoCrFeMnNi plastic deformation behavior under tensile and cyclic stress by using in-situ neutron diffraction. Then compare the tensile properties at room temperature between CoCrFeNi and CoCrFeMnNi in order to study the effect of adding manganese to HEA. The result shows the addition of manganese increases yield strength and ultimate tensile strength, but at the same time decreases the HEA elongation. Besides, the large grains in as-cast alloy allows the observation of the effect of twinning on plastic deformations of both HEA, CoCrFeNi and CoCrFeMnNi at room temperature. In low cycle fatigue experiment, the interaction between dislocation, twinning and dislocation wall dominates the fatigue behavior of CoCrFeMnNi.