Transformation-reinforced high-entropy alloys with superior mechanical properties via tailoring stacking fault energy

By Shixiang Liu, Y. Wu, Hui Wang, Weitong Lin, Y. Shang, Jiabin Liu, Ke An, X. J. Liu, H. Wang, Zhenwen Lu. Journal of Alloys and Compounds, 2019

159 citations recorded by the source corpus.

Abstract Face-centered cubic (fcc) HEAs, particularly the typical FeCoNiCrMn HEA, are promising for cryogenic applications but generally exhibit relatively low strength at ambient temperature, which limits their widespread uses. In this work, we present a systematic study of enhancing simultaneously the strength and ductility of FeCoNiCrMn HEAs via tailoring the phase stability and stacking fault energy (SFE). It was found that in Fe20CoxNi40-xCr20Mn20 (x = 20–30 at.%) HEAs, with the increase of Co, the SFE was gradually decreased and another hcp (hexagonal close-packed) phase was eventually formed in the alloy containing 28 at.% Co. As a result, the deformation mode changes from dislocation glide to mechanical twinning, then to γfcc → ehcp martensitic transformation. Our analysis indicates that the small critical shear stress for twinning resulted from the reduced SFE provides a steady strain hardening rate in a wide strain regime and postpones the plastic instability, eventually leading to the concurrent enhancement in the tensile strength and ductility. Our results not only shed lights on understanding of the effects of SFE on the mechanical properties, but also have important implications on the development of HEAs with a unique combination of high strength and large ductility.

Subfields: Aerospace Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/851e4a2d04ceadf2b8ded3ff89233cacb7248bcb