Investigating the potentialities of Ni3Al alloy formation on Ni substrates: Molecular dynamics simulation

H El Azrak and A Hassani and K Sbiaai and A Hasnaoui, JOURNAL OF CRYSTAL GROWTH, 537, 125607 (2020).

DOI: 10.1016/j.jcrysgro.2020.125607

This study aims to explore the potentialities of Ni3Al alloy formation on Ni substrates. For this purpose, depositions of Ni:Al mixture on Ni(0 0 1), Ni(1 1 0) and Ni(1 1 1) substrates according to a ratio of 3:1 were simulated by molecular dynamics. The common neighbor analysis revealed high crystalline structures rate within the grown thin films on all surfaces. The (1 1 0) surface generated the most ordered film with about 78% fcc structures. A rigorous counting of Al atoms in deposited layers and in the substrate has showed Al penetration into the substrate. Namely, Al penetration rates of 8%, 20% and 3% were recorded on (0 0 1), (1 1 0) and (1 1 1) surfaces, respectively. For the (1 1 0) surface, the relatively high penetration rate of Al in the sublayers promoted the formation of Ni3Al structure through exchange mechanisms. Due to high thermal agitation and space induced by channels, the strong vibration of atoms in Ni(1 1 0) substrate supported the exchange mechanisms especially for the superficial layers. Moreover, the Al coordination analysis showed that the (1 1 0) surface demonstrates a great potential to form Ni3Al more than Ni5Al3 phase contrary to (0 0 1) and (1 1 1) surfaces. In particular, the formed thin film on (1 1 0) surface contains 70% of Ni3Al phase, with 2/3 Al atoms on antisites, and 30% of Ni5Al3 phase in which 1/6 of Al atoms are on antisites. Finally, high temperature and low incidence energy increased the ability to form Ni3Al structures and decreased NiAl phases.

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