The solution treatment temperature and duration regulate the SIMT mechanism in laser powder bed fusion Ti-10V-2Fe-3Al alloys

Heat treatment is a crucial postprocessing step to tailor the microstructure and enhance the mechanical properties of additively manufactured titanium alloys. This study investigated the effects of solution treatment temperature and duration on the microstructural and mechanical properties of LPBF-fabricated Ti-1023, focusing on the activation and regulation of the stress-induced martensitic transformation (SIMT) mechanism. The as- fabricated sample exhibited a dual-phase ((3 + wiso). Increasing the solution temperature from 600 degrees C to 800 degrees C reduced alpha phase content from 52.7 % to 15.3 %. A prolonged duration at 900 degrees C(10-40 min) induced substantial (3 grain coarsening, maintaining a ((3 + w) phase. The as-fabricated sample displayed brittle fracture, whereas the solution treatments significantly improved elongation. At 800 degrees C, the elongation reached 16.6 %, and further extending the duration at 900 degrees C increased it to 23.0 %, due to SIMT activation. During LPBF processing, repeated thermal cycles lead to a high density of dislocations (average KAM = 0.67 degrees) and promote the transformation of the preprecipitated w into a hard and brittle wiso, both of which contribute to brittle fracture. Solution treatment eliminated dislocations and facilitated wiso -> alpha phase transformation (325-410 degrees C), whereas alpha phase precipitation stabilized (3 through Al depletion and Fe/V enrichment. The SIMT is influenced by (3 phase stability ([Mo]eq) and grain size. Increasing the solution temperature reduced [Mo]eq from 23.0 to 14.8, with the critical [Mo]eq range for SIMT activation being 14.8-15.4. At 900 degrees C, [Mo]eq stabilized at 10.1, while lager grain size reduced alpha '' martensite content and elongation. Additionally, solution treatment promotes elemental homogenization, with optimal homogenization achieved after 2.4 min at 900 degrees C, resulting in the maximum elongation.