Abstract
In this study, the grain boundary evolution of equiatomic CoCrFeMnNi, CoCrFeNi, and FeCoNi alloys after one-step recrystallization were investigated. The special boundary fraction and twin density of these alloys were evaluated by electron backscatter diffraction analysis. Among the three alloys tested, FeCoNi exhibited the highest special boundary fraction and twin density after one-step recrystallization. The special boundary increment after one-step recrystallization was mainly affected by grain boundary velocity, while twin density was mainly affected by average grain boundary energy and twin boundary energy.
Highlights
The concept of grain boundary engineering (GBE) has been previously proposed by Watanabe[1], and its aim is to improve resistance to oxidation, corrosion, creep, and the propagation of cracks in materials[2,3,4,5,6] by controlling the grain boundary character distribution (GBCD) with high special boundary population and broken interconnectivity of high angle grain boundaries (HAGBs)
The stacking fault energies of CoCrFeNi and CoCrFeMnNi have been measured by Zaddach et al.[22] using the x-ray diffraction method coupled with first principle calculations, and it has been reported that CoCrFeMnNi possesses lower stacking fault energy than that of CoCrFeNi
This study analyzed the effect of GBE on FCC high entropy alloy (HEA) system with alloying complexity ranging from 3 to 5 elements, and the results show that the alloying element and its amount can influence GBCD significantly
Summary
The concept of grain boundary engineering (GBE) has been previously proposed by Watanabe[1], and its aim is to improve resistance to oxidation, corrosion, creep, and the propagation of cracks in materials[2,3,4,5,6] by controlling the grain boundary character distribution (GBCD) with high special boundary population and broken interconnectivity of high angle grain boundaries (HAGBs). Hwang et al.[18] have observed another two types of special boundary interactions by in-situ electron backscatter diffraction (EBSD): (1) HAGB dissociation, which indicates the rapid migration of specific HAGBs being dissociated into Σ 3 boundaries because of a growth accident, and (2) annihilation of the special boundary by HAGB migration Each of these theories have helped to establish the underlying mechanisms for GBCD during GBE processes. Sluggish diffusion effects can hinder the grain boundary migration[19], and severe lattice distortion effects can impede dislocation movement and decrease stacking fault energy[21,22]. Both of these HEA effects can have significant effects on the GBCD. The underlying mechanisms of GBCD of high entropy, medium entropy, and lower entropy alloys have been discussed in this article
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