Additively manufactured heterogeneous precipitation-strengthened high-entropy alloys with high strength and ductility

作者：Xiao, Bo; Chen, Rong; Zhang, Jianyang; Zhang, Jixun; Zhou, Yinghao; Ju, Jiang; Zhao, Yilu; Xu, Lianyong; Yang, Tao^*

来源：Additive Manufacturing, 2023, 77: 103795.

DOI：10.1016/j.addma.2023.103795

• High-entropy alloys
• Additive manufacturing
• Structural heterogeneity
• Mechanical properties
• Deformation mechanisms

Heterogeneous-structured (HS) materials have drawn particular attention due to their extraordinary strength-ductility combinations. Benefiting from the large thermal gradient and high cooling rate, additive manufacturing (AM) enables structural and compositional heterogeneity at the multiscale, which provides new routines for high-performance HS materials. Here, we successfully fabricated a cellular-structured CoNiCrFeAlTi-based high-entropy alloy (HEA) by using the directed-energy deposition (DED) technology. Subsequent thermal treatment produces a distinctly different microstructure consisting of single-phase (face-centered cubic, FCC) interior and dual-phase (FCC + L12) wall, which leads to an ultrahigh tensile strength of-1148 MPa combined with a large ductility of-28 %. We attribute the high strength to the pronounced ordering strengthening from high-density L12-type precipitates in the wall while the large ductility primarily comes from the improved plastic deformation stability via hetero-deformation-induced strain hardening and deformation-induced stacking faults (SFs). Our current work is expected to open up a new area for designing high-performance HS multiple-principal-element alloys.

• 单位
  天津大学