Effect of Al/Ti ratio on the microstructure, texture and incipient plasticity of (CoNiCr0.5)95AlxTiy high entropy alloys

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2023-02, Vol.866, Article 144651
• Main Authors: Jiang, Hongwan, Lu, Yafang, An, Xulong, Qin, Jiaqing, Xie, Tianjin, Jin, Fengshuo, Zhou, Shengfeng, Li, Wei, Long, Shaolei, Yi, Yanliang
• Format: Article
• Language: English
• Subjects: High entropy alloy; Incipient plasticity; Mechanical property; Texture
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2023.144651

To analyze the incipient plasticity and then optimize the micromechanical behavior of HEAs, the FCC (CoNiCr0.5)95AlxTiy (x = 1, 3, 4 and y = 4, 2,1 (at.%)) HEAs were selected and thermomechanical processed, and corresponding microstructure, mechanical property and incipient plasticity were investigated and discussed. As the Al/Ti ratio changes from 1/4 to 4/1, the average GND of HEAs decreases from 1.11 × 1014 m−2 to 1.05 × 1014 m−2, and the contents of the A {110} and CopperTwin {552} reach to 11% and 4.4%, respectively. Meanwhile, the ductility of HEA increases from 10.6% to 13.9% with the increased Al/Ti ratio, while the strength decreases from 1221.1 MPa to 910.3 MPa. Nanoindentation results show that the normalized maximum stress τmax/μ of the HEAs exhibit the value of (1/18–1/12)μ, and the average activation volume v∗are calculated to be 3.2–3.4 Ω. These indicate that the incipient plasticity of (CoNiCr0.5)95AlxTiy possesses heterogeneous dislocation nucleation triggered by cooperative migration of multiple atoms via vacancies.