• Toku, Yuhki
• Ju, Yang
• Uchida, Motoki
• Kimura, Yasuhiro

Abstract

<jats:title>Abstract</jats:title><jats:p>Molecular dynamics studies were performed to assess tensile and compressive behaviors at high temperatures up to 1200 °C for nanostructured polycrystalline AlCoCrFeNi high entropy alloy (HEA). As the temperature increased, the tensile yield stress, tensile/compressive ultimate strengths, and elastic modulus decreased, whereas the compressive yield stress remained constant. The temperature dependence of the phase structures (face-centered cubic (FCC) and hexagonal close-packed (HCP)) showed notable features between tension and compression. The HEA underwent FCC → HCP phase transformation when strained under both tension and compression. The evolution of the intrinsic stacking faults (ISFs) and extrinsic stacking faults (ESFs), which underwent FCC → HCP phase transformation, was observed. During compression, the ISFs → ESFs transition produced parallel twins. The evolution of mean dislocation length for the perfect, Shockley, and stair-rod partial dislocations was observed. Changes in the Shockley and stair-rod partial dislocations were observed after experiencing strain. The temperature dependence of the Shockley partial dislocation was high, whereas the stair-rod partial dislocation exhibited low-temperature dependence. From the simulation results, the structural usage of nanostructured polycrystalline AlCoCrFeNi HEA at elevated temperatures is recommended.</jats:p>

Topics

• impedance spectroscopy
• phase
• simulation
• molecular dynamics
• strength
• dislocation
• stacking fault