Deformation Behavior of Pure Titanium With a Rare HCP/FCC Boundary: An Atomistic Study

Abstract

The compressive and tensile behaviors in a Ti nanopillar with a biphasic hexagonal close-packed (HCP) /face-centered cubic (FCC) phase boundary are theoretically researched using classic molecular dynamic simulation. The results indicate that the HCP/FCC interface and free surface of the nanopillar are the sources of dislocation nucleation. The plastic deformation is mainly concentrated in the metastable FCC phase of the biphasic nanopillar. Under compressive loading, a reverse phase transformation of FCC to the HCP phase is induced by the dislocation glide of multiple Shockley partial dislocations 1 6 <121> under compressive loading. However, for tensile loading a large number of Lomer-Cottrell sessile dislocations and stacking fault nets are formed when the partial dislocations react, which leads to an increase in stress. The formation mechanism of a Lomer-Cottrell sessile dislocation is also studied in detail. Shockley partial dislocations are the dominant mode of plastic deformation behaviors in the metastable FCC phase of the biphasic nanopillar.

The Plastic Deformation Mechanisms of hcp Single Crystals with Different Orientations: Molecular Dynamics Simulations

“…In Ti single crystals, phase transformation from hcp to fcc structure is observed at θ = 0°, θ ≥ 70°, and β = 15°–58.6°. In our simulation, the hcp-fcc phase transformation is accomplished via successive glide of basal partial dislocations, which has been observed in previous studies [ 28 , 54 , 60 ].…”

“…The surface and orientation effects on stress-induced hcp-fcc phase transformation in Ti nanopillars has also been investigated, recently [ 27 ]. The biphasic HCP/FCC phase boundary are theoretically researched using classic molecular dynamic simulation [ 28 ].…”

Role of Energetic Ions in the Growth of fcc and ω Crystalline Phases in Ti Films Deposited by HiPIMS

“…As reported in a recent theoretical work [63] related to the evolution of Ti fcc and α phases under compressive and tensile loadings, the presence of a compressive state induces the formation of Schokley partial dislocations that slip the crystalline planes from the (111) direction of the fcc to the (002) direction of the Ti α-phase. Interestingly in the article, a critical value of 2.5 GPa is calculated for the starting of the transition.…”

High-resolution STEM investigation of the role of dislocations during decomposition of Ti1-xAlxNy

“…The partial dislocations and SFs then initiate and facilitate the cubic-to-wurtzite transformation of AlN. Other materials that exhibit a cubic or zincblende to wurtzite transformation (and vice versa) have been shown to display a continuous glide of Shockley partial dislocations as the mechanism of the transformation [39,40]. Similar behaviors were found for AlN during nanoindentation, wherein the reversible transition between zinc blende to wurtzite happens by the collective glide of Shockley partials [41].…”