Molecular Dynamics Study of Ultrasonic Melt Processing of Aluminum Alloys

Run Wang; Siwei Sun

doi:10.6919/ICJE.202512_11(12).0026

Authors

Run Wang
Siwei Sun

DOI:

https://doi.org/10.6919/ICJE.202512_11(12).0026

Keywords:

Aluminum Alloys, Ultrasonic Melt Processing (USMP); Acoustic Cavitation, Molecular Dynamics (MD), Mean First-Passage Time (MFPT), Critical Nucleus Size, Nucleation Rate, Radial Distribution Function (RDF), Common-Neighbor Analysis (CNA); Al–Ti Alloy.

Abstract

Ultrasonic melt processing (USMP) is an efficient and environmentally friendly technique that can markedly refine the solidification microstructure of aluminum alloys and promote nucleation and fragmentation without the need for chemical additives. However, the opacity of metallic melts and the ultrashort timescale of acoustic cavitation events (≈20 ns) pose substantial challenges for direct experimental observation, necessitating atomistic simulations to provide quantitative insight..In this study, molecular dynamics (MD) simulations were employed to investigate cavitation-induced nucleation in an Al₇₇Ti₂₃ alloy melt. The results show that under acoustic cavitation, where the local pressure can reach as high as 100 atm, the critical nucleus size is significantly reduced from 18.9 atoms to 6.3 atoms, while the nucleation rate increases from 1.552×10³⁴m^-3s^-1 to 2.1×10³⁴m^-3s^-1, as quantified by the mean first-passage time (MFPT) method. Radial distribution function analysis together with common-neighbor analysis further reveals an accelerated development of structural order and enhanced crystal growth under cavitation, leading to a more uniform microstructure. These findings provide a molecular-level understanding of the mechanisms of USMP and help bridge transient cavitation dynamics with the observed improvements in alloy performance for aerospace and automotive applications.

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