Dislocation-nucleation-controlled deformation of Ni3Al nanocubes in molecular dynamics simulations

K Shreiber and D Mordehai, MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, 23, 085004 (2015).

DOI: 10.1088/0965-0393/23/8/085004

The strength of Ni3Al nanocubes under compression, as well as the underlying dislocation mechanisms, are analysed in molecular dynamics simulations. For this purpose, the bond-order parameters analysis is extended to multi-atomic systems in order to identify the intrinsic planar defects in Ni3Al. We benchmarked different interatomic potentials and compared the results with experimental ones. The different potentials resulted in different elastic responses under compression but all yielded abruptly at a compressive stress of about 7-8 GPa, followed by a large strain burst. The nanocubes yielded by nucleating Shockley partial dislocations at the vertices on 1 1 1 planes, leaving a structure of faulted planes. The mechanical response was found to be size independent, which we attribute to the cubical shape of the nanoparticle and the lack of stress gradients at its vertices.

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