Molecular dynamics study of microstructural evolution in Ti6Al4V alloy by laser melting

Understanding the evolution mechanism of alloy organization during selective laser melting (SLM) is crucial for adjusting process parameters and determining structural and organizational properties. However, it is very difficult to capture the corresponding microstructural change. This study employs molecular dynamics simulations to explore the microstructural evolution and laser melting behavior of Ti6Al4V nanoparticles at the atomic scale, which deepens the basic understanding of SLM. The nanoparticle size effect, structural changes, and sintering mechanism are investigated by establishing nanoparticle systems. The results demonstrate that surface diffusion and volume diffusion dominate the melting process, and surface atoms are more prone to pre-melting and violent movement. The melting temperature of nanoparticles depends on their size, with smaller-sized nanoparticles having a lower melting temperature. Varying size ratios in the two-nanoparticle system result in inconsistent diffusion and wetting rates of smaller nanoparticles. As the size ratio increases, small nanoparticles more easily diffuse and wet large ones. Furthermore, the melting behavior of a multiple-nanoparticle system is investigated.