Engulfment and Pushing of Cylindrical Liquid Nano-Inclusion by Advancing Crystal/Melt Interface: An Atomistic...

Area of Science:

• Materials Science
• Physical Chemistry
• Computational Materials Science

Background:

• Solidification processes are crucial in materials manufacturing.
• Understanding the interaction between crystalizing metals and foreign inclusions is vital for controlling material properties.
• Previous studies have explored similar phenomena, but a detailed investigation into the velocity-dependent behavior of cylindrical nano-inclusions is needed.

Purpose of the Study:

• To investigate the engulfment or pushing of cylindrical liquid lead (Pb) nano-inclusions by a growing pure aluminum (Al) crystal.
• To determine the critical velocity (vc) that dictates the interaction outcome.
• To establish a relationship between vc and the nano-inclusion radius.

Main Methods:

• Molecular dynamics (MD) simulations were employed to model the Al(100)/melt interface.
• The simulation focused on an advancing interface encountering a cylindrical liquid Pb nano-inclusion.
• Parameters such as interface velocity and nano-inclusion radius were systematically varied.

Main Results:

• A critical velocity (vc) was deduced, separating two distinct interaction regimes.
• Below vc, the liquid Pb nano-inclusion is pushed and subsequently engulfed by the growing Al crystal.
• Above vc, the Al crystal interface hinders atomic rearrangement, leading to engulfment of the Pb nano-inclusion.
• A power-law relationship between vc and nano-inclusion radius was identified, consistent with prior research.

Conclusions:

• The velocity of the crystal/melt interface is a key factor governing the fate of foreign nano-inclusions during solidification.
• Insufficient mass transfer beneath the inclusion at velocities above vc leads to engulfment.
• The findings provide insights into controlling microstructure and properties in alloys containing inclusions.