Enhancing mechanical properties of the boron doped Al0.2Co1.5CrFeNi1.5Ti0.5 high entropy alloy via tuning composition and microstructure

• Published in: Journal of alloys and compounds 2022-03, Vol.896, p.162852, Article 162852
• Main Authors: Xin, Benbin, Zhang, Aijun, Han, Jiesheng, Zhang, Junyan, Meng, Junhu
• Format: Article
• Language: English
• Subjects: Borides; Boron; Boron doping; Dendritic structure; Doping; Electric arc melting; Eutectic; Evolution; Heterostructures; High entropy alloy; High entropy alloys; Lamellar structure; Laves phase; Mechanical properties; Mechanical property; Microstructure; Solid solutions; Solution strengthening; Titanium diboride; Vacuum arc melting
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.162852

•A series of boron doped Al0.2Co1.5CrFeNi1.5Ti0.5Bx HEA was firstly reported.•Boron doping induces the transformation of microstructure from dendrite to eutectic.•The eutectic structure with lamellar morphology composed by FCC and Laves phase.•Boron doping improves mechanical properties of the HEAs significantly. [Display omitted] High entropy alloys (HEAs) have attracted considerable attention due to their excellent mechanical properties, which provides new insights for designing next generation structural materials. A series of Al0.2Co1.5CrFeNi1.5Ti0.5Bx (x = 0, 0.15, 0.3, 0.45, 0.6, 0.75 and 0.9, in molar ratio) HEAs was prepared by vacuum arc melting to investigate the effect of boron doping on the phase evolution, microstructure transformation and mechanical properties. The results indicated that the HEAs with trace boron doping (x = 0.15) maintained single FCC phase, while it evolved to FCC phase, in-situ borides (TiB2 and Cr2B) and Laves phase when the boron molar ratio higher than 0.3. With the boron molar content increased from 0 to 0.9, the microstructures of the HEAs transformed from complete dendrite to dendrites, irregularly shaped TiB2, needle-shaped Cr2B and lamellar eutectic structure which composed by alternate layers of FCC phase and Laves phase. B doping improved the strength and hardness of the HEAs. The enhanced mechanical properties of the boron doped HEAs was attributed to the synergistic strengthening effect among interstitial solid solution strengthening, second phase strengthening, dislocation strengthening, fine grain strengthening and heterostructure strengthening.