Effect of Zener–Hollomon parameter on hot deformation behavior of CoCrFeMnNiC0.5 high entropy alloy
Materials Science and Engineering: A(2019)
Abstract
Hot compressive deformation mechanism of the carbon-contained face-centered cubic CoCrFeMnNi high-entropy alloy (HEA) was investigated in the temperature range between 700 °C and 1000 °C and in the strain rate range between 0.001 and 1 s−1. The constitutive equation of CoCrFeMnNiC0.5 (at.%) alloy was obtained, which can predicate the flow stresses accurately. The apparent activation energy (Q) was calculated as 362 kJ/mol, suggesting that the carbon addition cause the work hardening during hot deformation. The deformation mechanisms at various Zener–Hollomon parameter values have been discussed. The Zener-Hollomon parameter (lnZ) of CoCrFeMnNiC0.5 alloy deformed at 700 °C increases with the increasing of the strain and strain rate. At low Zener-Hollomon condition (lnZ≤40), density dislocation walls (DDWs) caused the obvious work hardening by producing a long-range back stress. With the lnZ increasing, the addition of carbon in solid solution effectively reduces the dislocation cross-slip, and causes the transition from well-development DDWs to microbands (MBs). MBs can be regarded as another imported deformation mode to provide additional work-hardening source. At high Zener-Hollomon condition (lnZ>46), the pronounced effect of MBs results in slight increasing of the flow stress after steady flow. The Zener-Hollomon parameter of CoCrFeMnNiC0.5 HEA deformed at ε = 0.8 decreases with the temperature increasing and strain rate decreasing. Discontinuous dynamic recrystallization (DDRX) is the dominant microstructural evolution mechanism and leads the flow softening at low lnZ condition (lnZ≤40). The DDRX nucleation is attributed to the microbands and pinning effect on the dislocation movement induced by M23C6 carbides, which can lead to local grain boundary expansion.
MoreTranslated text
Key words
High entropy alloy,Carbon,Deformation mechanism,Zener–Hollomon parameter,Work-hardening rate,Discontinuous dynamic recrystallization
AI Read Science
Must-Reading Tree
Example
![](https://originalfileserver.aminer.cn/sys/aminer/pubs/mrt_preview.jpeg)
Generate MRT to find the research sequence of this paper
Chat Paper
Summary is being generated by the instructions you defined