Underlying mechanisms of enhanced plasticity in Ti/Al laminates at elevated temperatures: A molecular dynamics study

Abstract

The Ti/Al laminated metal components have attracted considerable attention due to their impressive strength and lightweight properties, positioning them as promising materials for aerospace and automotive applications. Although experimental evidence has highlighted their exceptional elongation and formability at elevated temperatures, there is still limited understanding of the underlying atomic-level mechanisms governing high-temperature plastic deformation, particularly with regards to the titanium aluminide (TiAl3) layer. This study utilized molecular dynamics (MD) simulations to investigate the tensile deformation of Ti/Al laminates, emphasizing the effects of temperature and TiAl3 layer thickness on atomic structural evolutions and mechanical properties. The MD simulations confirmed the decreases in the elastic modulus and peak stress at elevated temperatures, consistent with the experimental findings. The total dislocation length displayed an increasing trend with temperature, reaching a maximum at 600 K, before decreasing at 900 K due to amorphization. Moreover, the coordinated deformation among the Ti, Al and TiAl3 layers at elevated temperatures contributed to enhanced plasticity of the Ti/Al laminates. Furthermore, the TiAl3 layer thickness positively influenced the total dislocation length. However, increasing the layer thickness also leads to more high-strain bands in the TiAl3 layer, resulting in crack nucleation and decreased ductility of the Ti/Al laminate. This study provides valuable insights into the plastic deformation of Ti/Al laminates at elevated temperatures from the molecular dynamics perspective, benefitting further improvement in their plastic forming technique and engineering applications.

Keywords

• Ti/Al laminated composite
• TiAl3 intermetallic compound
• High-temperature plasticity
• Molecular dynamics