Effect of Heat Treatment on Selective Laser Melted Ti6Al4V Alloys by adding Ta: Microstructure & Mechanical Properties

Abstract

This study investigates the effect of heat treatment on the microstructure and mechanical properties of (Ti6Al4V)₉₂Ta₈ alloys produced by Selective Laser Melting. This research is motivated by the limited understanding of how β-stabilizing elements such as tantalum (Ta) influence phase evolution and mechanical performance in additively manufactured titanium alloys. The samples were subjected to heat treatment to compare as-built and heat-treated conditions. Microstructural characterization was performed using scanning electron microscopy to examine morphological changes, phase development, and Ta distribution. Mechanical testing included hardness measurements, tensile tests, and fatigue strength evaluations to assess variations in material response. After heat treatment, the alloy exhibited increased hardness and ductility, accompanied by higher strain and elastic modulus. However, ultimate tensile strength, yield strength, and fatigue strength decreased. These results indicate a transition toward more ductile behavior caused by microstructural coarsening and phase redistribution. Unmelted Ta particles persisted within the Ti6Al4V matrix due to the limited melting capability of SLM, while annealing promoted localized diffusion and grain reorientation around these regions. Overall, this study provides insight into the interaction between alloy composition, thermal treatment, and mechanical properties, highlighting the importance of optimizing heat treatment conditions to achieve a balanced combination of strength, ductility, and structural stability in SLM-produced titanium alloys.