Atomistic Investigation of the Titanium Carbide MXenes under Impact Loading

2D Titanium carbide MXenes with a structural formula recognized as Ti(n+1)C(n) have attracted attention from both the academic and industry fields due to their intriguing mechanical properties and appealing potential in a variety of areas such as nano-electronic circuits/devices, bio sensors, energy storage and reinforcing material for composites. Based on mutli-body comb3 (third-generation Charge-Optimized Many-Body) potential, this work investigated the impact resistance of monolayer Ti(n+1)C(n) nanosheets (namely, Ti(2)C Ti(3)C(2) and Ti(4)C(3)) under hypervelocity up to 7 km/s. The deformation behavior and the impact resist mechanisms of Ti(n+1)C(n) nanosheets were assessed. Penetration energy is found to positively correlate with the number of titanium atom layer (n). However, in tracking atomic Von Mises stress distribution, Ti(2)C exhibits the most significant elastic wave propagation velocity among the examined nanosheets, suggesting the highest energy delocalization rate and stronger energy dissipation via deformation prior to bond break. Consistently, Ti(2)C presents superior specific penetration energy due its Young’s-modulus-to-density ratio, followed by Ti(3)C(2) and Ti(4)C(3), suggesting an inverse correlation between the titanium atom layer number and specific penetration energy. This study provides a fundamental understanding of the deformation and penetration mechanisms of titanium carbide MXene nanosheets under impact, which could be beneficial to facilitating their emerging impact protection applications.