This study investigates the influence of heat treatment on the microstructure and elemental distribution in TIG-welded joints between Ti-6Al-4 V alloy (ASTM Grade 5) and Ti (ASTM Grade 2). The welding joints were formed from the molten state, followed by heat treatment consisting of uniform annealing of solid solution, quenching at 900 °C, and aging the alloy at different temperatures. The microstructure of the welding joint and heat-affected zone was observed using optical microscopy (OM) and scanning electron microscopy (SEM), focusing on the distribution of α and β phases. Furthermore, the distribution of Al, Ti, and V elements in these phases at the welding joint and the heat-affected zone was analyzed to evaluate the influence of heat treatment on the compositional distribution of these elements and the microstructure of the weld boundary and surrounding areas.