Dislocations interaction induced structural instability in intermetallic Al2Cu

Abstract

Intermetallic precipitates are widely used to tailor mechanical properties of structural alloys but are often destabilized during plastic deformation. Using atomistic simulations, we elucidate structural instability mechanisms of intermetallic precipitates associated with dislocation motion in a model system of Al 2 Cu. Interaction of non-coplanar <001> dislocation dipoles during plastic deformation results in anomalous reactions-the creation of vacancies accompanied with climb and collective glide of <001> dislocation associated with the dislocation core change and atomic shuffle-accounting for structural instability in intermetallic Al 2 Cu. This process is profound with decreasing separation of non-coplanar dislocations and increasing temperature and is likely to be operative in other non-cubic intermetallic compounds as well.

Superplastic Deformation of Al–Cu Alloys after Grain Refinement by Extrusion Combined with Reversible Torsion

“…This situation was connected with the fact that for Al 2 Cu phase, the processes of recovery can proceed easier than for the α-Al phase. The obtained results are in accordance with the literature [ 24 , 25 ]. During deformation in Al 2 Cu phase, we observed a mechanism connected with non-conservative motion of glide dislocation.…”

“…The high population of vacancies observed in Al 2 Cu alloys facilitated the diffusion of the alloying elements; thus, it may have accelerated de-alloying of Al from Al 2 Cu. In addition, it is conjectured that the easy climb of dislocations driven by dislocation interaction will reduce the glide ability of a dislocation, limiting plastic shear under mechanical loading [ 25 ].…”

Manipulation of Phonon Transport in Thermoelectrics

“…Furthermore, charged defects, either substitutional atoms or vacancies, have strong electrostatic interactions with charged dislocations (such as jogs), which not only promote the climb of dislocations but also retard their annihilation . Such a mechanism of dislocation climb for increasing the density of dislocations has been discussed in more detail in intermetallic compounds . It has also been reported that introducing both isovalent and aliovalent impurities in PbTe leads to a transition of the dominant microstructural defects from point defects, to dense in‐grain dislocations, and then to nanoprecipitates by controlling the initial composition of the material ( Figure a–c) .…”

Boundary Condition for Dislocation Dynamic Simulation in BCC Crystal

“…It is widely agreed that dislocations are the main carrier of plastic deformation in crystalline materials. The movement of dislocations is the key mechanism of strain energy relaxation which is highly influenced by the interaction with other defects, external loads and crystal structures [1][2][3][4][5][6]. Therefore it is important to note that the development of an accurate plasticity theory should based on the detailed dislocation mechanics that the movement of each dislocation could be traced, rather than on empirical assumptions [1,7].…”