Abstract
In order to efficiently explore the nearly infinite composition space in multicomponent solid solution alloys for reaching higher mechanical performance, it is important to establish predictive design strategies using computation-aided methods. Here, using ab initio calculations we systematically study the effects of magnetism and chemical composition on the generalized stacking fault energy surface (γ-surface) of Cr-Co-Ni medium entropy alloys and show that both chemistry and the coupled magnetic state strongly affect the γ-surface, consequently, the primary deformation modes. The relations among various stable and unstable stacking fault energies are revealed and discussed. The present findings are useful for studying the deformation behaviors of Cr-Co-Ni alloys and facilitate a density functional theory based design of transformation-induced plasticity and twinning-induced plasticity mechanisms in Cr-Co-Ni alloys.
Highlights
High entropy alloys (HEAs) were originally proposed by Yeh and Cantor in 2004 [1,2] as equiatomic concentrated solid solutions, which stabilize the single-phase structure through the maximized configurational entropy
The mechanical properties of these HEAs are further improved at cryogenic temperatures, which are ascribed to the enhanced transformation-induced plasticity (TRIP)/twinning-induced plasticity (TWIP) effects via the occurrence of twin + hexagonal close packed lamellar structure, partly due to the temperature effect on the stacking fault energy (SFE) [4]
Some Cr-Co-Ni-based HEAs exhibit excellent mechanical properties at cryogenic temperatures [3,44], which are related to the underlying deformation mechanisms activated/enhanced at low temperatures
Summary
High entropy alloys (HEAs) were originally proposed by Yeh and Cantor in 2004 [1,2] as equiatomic concentrated solid solutions, which stabilize the single-phase structure through the maximized configurational entropy. Li et al [9] proposed the socalled ‘metastability-engineering strategy’ in Cr-Mn-Fe-Co alloys to optimize the mechanical performance, which represents one guideline of designing HEAs. The composition of the alloy was modified in order to trigger the transformation-induced plasticity (TRIP) [9,10] or the twinning-induced plasticity (TWIP) effects [11,12]. The composition of the alloy was modified in order to trigger the transformation-induced plasticity (TRIP) [9,10] or the twinning-induced plasticity (TWIP) effects [11,12] This design concept combines the benefits from the massive solid solution hardening in HEAs with the TRIP/TWIP effects. The mechanical properties of these HEAs are further improved at cryogenic temperatures, which are ascribed to the enhanced TRIP/TWIP effects via the occurrence of twin + hexagonal close packed (hcp) lamellar structure, partly due to the temperature effect on the stacking fault energy (SFE) [4]
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