Oxygen greatly affects the mechanical properties of titanium. In addition, dislocations and twin boundaries influence the plastics deformation of hexagonal close-packed metals. As part of a systematic study of defects interactions in Ti, we investigate the interactions of oxygen with ð10 12Þ twin boundaries and ð10 10Þ prism plane stacking faults. The energetics of four interstitial sites in th...

Nanocrystalline nc materials are known to deform via mechanisms not accessible to their coarse-grained counterparts. For example, deformation twins and partial dislocations emitted from grain boundaries have been observed in nc Al and Cu synthesized by severe plastic deformation SPD . This paper further develops an earlier dislocation-based model on the nucleation of deformation twins in nc fac...

The accurate determination of stacking fault energies (SFE) and associated restoring forces is important for understanding plastic deformation, especially the dislocation emission and motion in metals. In this work, we use density-functional theory (DFT) calculations to, systematically study the all-dimension relaxed atomic models of Mg crystal slip, with a special focus on the “subslip modes” ...

We compute the structural energies, elastic constants, and stacking fault energies, and investigate the phase stability of monoborides with different compositions (X1 1−xX 2 x)B (X = Ti/Fe/Mo/Nb/V) using density functional theory in order to search for Ti monoborides with improved mechanical properties. Our computed Young’s modulus and Pugh’s modulus ratio, which correlate with stiffness and to...

In Ni-base superalloys, superlattice extrinsic stacking fault (SESF) shearing of c0 precipitates involves coupled dislocation glide and atomic diffusion. A phase-field model is developed to study this process, in which the free energy of the system is formulated as a function of both displacement and long-range order parameter. The free energy surface is fitted to various fault energy data obta...

Through high-resolution electron microscopy, stacking faults (SFs) due to Frank partial dislocations were found in an aluminum alloy following deformation with low strain and strain rate, while also remaining stable during artificial aging. Extrinsic stacking faults were found surrounded by dislocation areas and precipitates. An intrinsic stacking fault was found between two Guinier-Preston II ...

We have employed the semidiscrete variational generalized Peierls-Nabarro model to study the dislocation properties of aluminum. The generalized-stacking-fault ~GSF! energy surface entering the model is calculated by using first-principles density functional theory ~DFT! and the embedded-atom method ~EAM!. Various core properties, including the core width, dissociation behavior, energetics, and...

We have employed the semidiscrete variational generalized Peierls-Nabarro model to study the dislocation core properties of aluminum. The generalized stacking fault energy surfaces entering the model are calculated by using first-principles Density Functional Theory (DFT) with pseudopotentials and the embedded atom method (EAM). Various core properties, including the core width, splitting behav...