String-like collective motion mediates the martensitic α-β transition in titanium

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Recent studies highlight string-like collective atomic motion in cooled liquids and crystalline materials.
• This motion is crucial for understanding non-Arrhenius dynamics in various material systems.
• Previous work focused on equilibrium conditions, examining structural relaxation time and atomic diffusivity.

Purpose of the Study:

• To investigate the role of string-like collective motion in the α-β displacive structural transition of titanium.
• To analyze the dynamics of the phase transformation process in crystalline metals.
• To extend the understanding of collective motion beyond equilibrium conditions.

Main Methods:

• Employed molecular dynamics simulations.
• Focused on crystalline titanium undergoing the α-β phase transition.
• Analyzed the relationship between collective motion scale and transition dynamics.

Main Results:

• Observed a progressive decrease in the scale of collective motion with increasing temperature above the transition point.
• Found that the activation free energy of the new phase interface correlates with average string length (Ls).
• Discovered that strings are localized in temperature-dependent channels within the crystal during the transition.

Conclusions:

• String-like collective motion plays a critical role in mediating the α-β displacive transition in titanium.
• The dynamics of the phase transformation are significantly influenced by this collective atomic movement.
• This study provides another physical example demonstrating the importance of collective motion in material dynamics.