Effect of rate dependence of crack propagation processes on amorphization in Al

PT Li and YQ Yang and X Luo and N Jin and G Liu and CD Kou and ZQ Feng, MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 684, 71-77 (2017).

DOI: 10.1016/j.msea.2016.12.053

I.Tniaxial tension of pure Al is studied at different loading rates by molecular dynamics simulation to understand the initial nucleation processes for amorphous structures and twinning, especially, the competition between twinning partial dislocation and Lomer one. There exists a transition point K-I=0.205 eV angstrom(-2.5) between twinning partial dislocation and Lomer one, with Lomer dislocation preferable at high loads. A modified Peierls analytic model is established to describe the transition process. The analytic model reflects that a transition from twinning partial dislocation to Lomer one will occur when stress intensity factor K-I reaches 0.205 eV angstrom(-2.5), which is similar to the simulation trends. In addition, amorphization behaviours are observed at crack tip in pure Al by in-situ straining transmission electron microscopy. Both the experiment and simulation results are demonstrated that amorphization behaviours occur at crack tip in FCC Al.

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