Effects of solidification defects on nanoscale mechanical properties of rapid directionally solidified Al-Cu Alloy: A large scale molecular dynamics study

Directional solidification of Al-11 at % Cu is investigated by molecular dynamics (MD) simulations utilizing second nearest neighbor modified embedded atom method (2NN-MEAM) interatomic potential. The condition for directional solidification is produced by imposing dissimilar temperatures at the model boundaries along the [1 0 0] solidification direction to create a temperature gradient. During solidification, the solid-liquid front travels through the Al-Cu liquid along the [1 0 0] direction towards the high temperature end. At the initial stages of solidification, several solidification defects such as twins, stacking faults, and grain boundaries form. As directional solidification progresses, grains elongate along the solidification direction, and at the final stages of solidification no new defects or grain boundaries form. The elongated grain boundaries form a few layers with lamellar like structures along [1 0 0]. When the solidified polycrystalline is deformed in the [0 0 1] direction, glide of partial dislocations happen around the grain boundaries, whereas during elongation along [1 0 0] some defects from in the Al-Cu matrix. Since formation of defects requires more energy, the solidified samples show a higher tensile strength and strain when deformed along the [1 0 0] solidification direction.

Journal of Crystal GrowthVolume 527, 1 December 2019, 125255 Download from here: https://authors.elsevier.com/a/1Zq8N50WDX~Zz