Structural damage and phase stability of Al0.3CoCrFeNi high entropy alloy under high temperature ion irradiation

• Published in: Acta materialia Vol. 188; pp. 1 - 15
• Main Authors: Yang, Tengfei, Guo, Wei, Poplawsky, Jonathan D., Li, Dongyue, Wang, Ling, Li, Yao, Hu, Wangyu, Crespillo, Miguel L., Yan, Zhanfeng, Zhang, Yong, Wang, Yugang, Zinkle, Steven J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 15.04.2020; Elsevier
• Subjects: High entropy alloy; Irradiation effect; MATERIALS SCIENCE; Phase stability; Structural damage; Phase stability; Irradiation effect; High entropy alloy; Structural damage
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2020.01.060

An initially single phase high entropy alloy (HEA) Al0.3CoCrFeNi was irradiated by 3 MeV Au ions to a fluence of 6 × 1015 cm−2 (∼31 dpa at damage peak) at four different temperatures ranging from 250 °C to 650 °C. Transmission electron microscopy (TEM) and Atom probe tomography (APT) were employed to study the evolution of structural damage and phase stability with irradiation temperature. Al0.3CoCrFeNi exhibited a similar evolution of irradiation-induced defects with temperature as compared with conventional FCC alloys. At 250 °C and 350 °C, most of the visible irradiation-induced defects were faulted 1/3〈111〉 dislocation loops. As the irradiation temperature increased to 500 °C, perfect 1/2〈110〉 dislocation loops were observed along with the faulted loops. At the highest irradiation temperature 650 °C, only dislocation lines and networks could be observed. Regarding phase stability, the 3 MeV Au irradiation was observed to suppress the precipitation of (Ni, Al)-enriched nano clusters and the L12 ordered structure at irradiation temperatures 250 °C to 500 °C whereas precipitation of the B2 ordered structure was accelerated at 650 °C. This resulted in qualitatively opposite precipitation behavior between the ion irradiated damage region and unirradiated region at 500 °C and 650 °C. The opposite phase stability of the ion-irradiated damage region and unirradiated region at different temperatures is attributed to the competing effects of ballistic dissolution vs irradiation enhanced diffusion on precipitation. [Display omitted]