Elucidating Interfacial Dynamics of Ti-Al Systems Using Molecular Dynamics Simulation and Markov State Modeling

Area of Science:

• Materials Science
• Metallurgy
• Computational Materials Science

Background:

• Titanium-aluminum (Ti-Al) based materials offer exceptional mechanical and chemical properties, driving interest in automotive, aerospace, and defense engineering.
• Despite their advantages, Ti-Al alloys often suffer from brittleness and defects after additive manufacturing and heat treatment, hindering their application.
• Understanding interfacial dynamics is key to overcoming these manufacturing challenges.

Purpose of the Study:

• To investigate the interfacial dynamics of Ti-Al systems during heat treatment, focusing on TiAl3 grain boundary behavior.
• To elucidate the kinetic processes governing TiAl3 formation at the atomic level.
• To provide insights for optimizing the manufacturing of Ti-Al based materials.

Main Methods:

• Employed molecular dynamics (MD) simulations to observe atomic behavior under heat treatment conditions.
• Utilized Markov state modeling (MSM) to analyze the dynamic states and spatial distributions of atoms.
• Examined transition time scales to quantify the rapidity of atomic diffusion processes.

Main Results:

• MD simulations showed initial Al atom diffusion towards the Ti surface via TiAl3 grain boundaries during heat treatment.
• MSM identified three distinct dynamic states for Al atoms in the Ti/Al mixture, each with unique spatial distributions.
• Al atom dynamics were significantly slower near the Ti surface compared to the Al surface.

Conclusions:

• A three-stage diffusion mechanism for TiAl3 formation was revealed: Al premelting, diffusion to the Ti surface, and cessation due to increasing Ti concentration.
• The study provides a comprehensive understanding of interfacial dynamics in Ti-Al systems.
• These findings can guide the control and optimization of manufacturing processes for high-performance Ti-Al materials.