Molecular dynamics study of the microstamping of TiAl6V4 alloy

Context

Microstamping has been shown to enhance the surface strength of alloy materials by improving interatomic density. This paper delves into the damage mechanism of TiAl6V4(TC4), which has been processed using high-speed stamping with varying overlap ratios at the atomic level. Additionally, the general trend of stress variation between loading and unloading is discussed. The mechanical properties of the substrate and the changes in microstructure resulting from varying overlap rates in microstamping were investigated. The impact of different machining overlap ratios on the depth of the damaged layer, the number of dislocation density lines, and the density of the matrix is also explored. The results indicate that the dislocation density remains relatively unchanged due to material hardening, while the overlap ratio increases continuously. Based on this analysis, a more optimal microstamping overlay ratio parameter is proposed to effectively enhance the surface strength of the substrate and reduce processing time.

Method

First, an alloy model with titanium, aluminum, and vanadium was created in ATOMSK and LAMMPS software. The model was divided into three layers: fixed, constant temperature, and Newton. To ensure the accuracy of the simulation, the system was annealed in order to minimize energy and replicate real-world conditions. Zhou’s EAM alloy potential was employed to represent the interaction between the alloy atoms, while the Tersoff potential was used to represent the interatomic interaction of the diamond indenter. Additionally, the LJ potential function was selected to depict the interaction between the metal atom and the diamond indenter. The construct surface mesh method in OVITO software was then utilized to construct a surface mesh and analyze the impact of different machining overlap rates on surface topography. The common neighborhood analysis (CNA) module in OVITO was used to calculate the number of defective atoms and the depth of the damaged layer. Finally, the DXA (dislocation extraction analysis) module in OVITO was used to calculate the dislocation density length and dislocation density.