Chemical short range order strengthening in a model FCC high entropy alloy

Unusual activated processes controlling dislocation motion in body-centered-cubic high-entropy alloys

“…The unstable stacking fault energies were found to be comparable to pure V. The 1/2<111> screw dislocation core described is nonplanar, spreading on several {110} planes like pure BCC metals. Fourth, this model potential has been recently used to study the dislocation behavior (31) and mechanical deformation-induced surface roughness (32) The Calculation of Chemical Short-Range-Order Parameters. The pairwise multicomponent short-range-order (SRO) parameters are defined as α m ij = (p m ij − C j )=(δ ij − C j ), where δ ij = 1 if i = j and 0 otherwise, p m ij is the probability of finding a j-type atom near the i-type atom in shell m and C j is the average concentration of j-type atom in the system.…”

“…The unstable stacking fault energies were found to be comparable to pure V. The 1/2<111> screw dislocation core described is nonplanar, spreading on several {110} planes like pure BCC metals. Fourth, this model potential has been recently used to study the dislocation behavior ( 31 ) and mechanical deformation-induced surface roughness ( 32 ) in an FCC Co 30 Fe 16.67 Ni 36.67 Ti 16.67 high-entropy alloy. However, the specific potential we used, while predicting a qualitative difference from a conventional BCC metal, should be taken as an empirical HEA model and not literally the real-world Co 16.67 Fe 36.67 Ni 16.67 Ti 30 .…”

Simultaneously enhancing the ultimate strength and ductility of high-entropy alloys via short-range ordering

“…Therefore, we turn to atomic-scale simulation tools to deepen our understanding of the SRO/mechanical behavior relationship in HEAs. The longer-time and larger-system size accessible with atomistic-simulation techniques, such as molecular dynamics (MD) 27 , 28 and Monte Carlo (MC) 29 – 31 , can provide insight into nanoscale phenomena in HEAs that are not easily accessible via first-principle calculations 32 , 33 . For example, Li et al 27 performed MD simulations of a nanocrystalline CoNiFeAl 0.3 Cu 0.7 HEA with grain sizes comparable to those in the experiments of Fu et al 34 and showed that the higher yield strength of the CoNiFeAl 0.3 Cu 0.7 HEA (1.8 GPa compared with most other FCC HEAs, 0.2–0.6 GPa) 35 – 37 was associated with a strain-induced FCC to BCC phase transition.…”

“…Hybrid MC/MD simulations have proven to be a powerful tool to explore the effects of atomic segregation and SRO on the mechanical properties of MEAs and HEAs 29 – 31 . For example, Jian et al 29 used hybrid MC and MD simulations to investigate the role of lattice distortion (LD) and SRO on the formation and evolution of dislocations in a CoCrNi MEA.…”

Atomistic simulations of dislocation mobility in refractory high-entropy alloys and the effect of chemical short-range order

“…Although HEAs possess crystalline order, but compositional disorder, they are not necessarily random solid solutions for every atomic species 29 – 37 . Specifically, a feature of HEAs is the possibility of the presence of local chemical short-range order (SRO), which can affect defect motion and hence may influence mechanical properties 27 , 30 , 38 , 39 .…”