Effect of heat treatment on microstructure and mechanical properties of as-cast AlCoCrFeNi2.1 eutectic high entropy alloy

• Published in: Journal of alloys and compounds Vol. 939; p. 168843
• Main Authors: Peng, Peng, Feng, Xiaoning, Li, Shengyuan, Wei, Baolin, Zhang, Mingyu, Xu, Yuanli, Zhang, Xudong, Ma, Zhikun, Wang, Jiatai
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.04.2023
• Subjects: Compressive properties; Heat treatment; High-entropy eutectic alloy; Precipitation; Tensile test; High-entropy eutectic alloy; Heat treatment; Precipitation; Compressive properties; Tensile test
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2023.168843

In this work, the effect of heat treatment on the microstructure and mechanical properties of as-cast AlCoCrFeNi2.1 eutectic high entropy alloy (EHEA) at 600 ℃, 700 ℃, 800 ℃, 1000 ℃ and 1200 ℃ for 1 h, 2 h, 4 h, 10 h and 50 h are investigated. Under heat treatment at 600 ℃, 700 ℃ and 800 ℃, the FCC phase (CoCrFe phase) precipitates in the B2 phase, which improves the tensile strength (from 1007 MPa to 1173 MPa) and compression strength (from 1847 MPa to 2850 MPa), but declines the elongation (from 18.4% to 13.3%) and compression strain (from 43% to 39%). Meanwhile, the precipitate fraction increases with increasing temperature and the size of precipitated phase increases with increasing holding time at 600 ℃, 700 ℃ and 800 ℃. After holding at 1000 ℃ and 1200 ℃, the FCC phase dissolves in the B2 phase, which softens the alloy. The elongation (from 18.4% to 20.3%) and compression strain (from 43% to 49%) increase and the alloy still remains good tensile and compression strength. This work indicates the mechanisms of heat treatment on the microstructure and mechanical properties of the alloy. •Fine precipitates is obtained in primary phase of AlCoCrFeNi2.1 EHEAs.•Precipitation phenomenon in primary phase is qualitatively analyzed by the nucleation theory for solid phase transformation.•Relationship between the microstructure and mechanical properties is clarified.