Outstanding tensile properties of a precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy at room and cryogenic temperatures

https://par.nsf.gov/servlets/purl/10186325

Promising properties and future trend of eutectic high entropy alloys

Fully recrystallized CoCrFeMnNi high entropy alloys (HEAs) with different grain sizes ranging from 503 nm to 88.9 µm were fabricated by cold rolling and controlled annealing. Tensile tests were conducted at ambient temperature, and deformation microstructures were investigated using electron channeling contrast imaging (ECCI) and transmission electron microscopy (TEM) techniques. It is found that strain-hardening curves changed dramatically with grain refinement. Deformation twinning prevails when the grain size is coarse, but it is absent when the grain size falls in the ultrafine-grained (UFG) regime. The transition of twinning behavior is supposed to be determined by the increased twinning stress with grain refinement. It is indicated that the twinning behavior of the HEAs is strongly dependent on the competition between the flow stress and critical twinning stress with grain refinement.

Qiao Dongxu

Papers

Effect of Niobium on Microstructure and Properties of the CoCrFeNbxNi High Entropy Alloys