Effect of alloying elements on laser surface modification of powder metallurgy to improve surface mechanical properties of beta titanium alloys for biomedical application

Beta-type titanium alloy surfaces (Ti–35Nb–10Ta (TNT) and Ti–30Nb–4Sn (TNS)) were modified by laser using a power of 1000 W and speed of 6.7 mm/s (Condition A) and a power of 1500 W with speed of 10 mm/s (Condition B). Increasing laser conditions, the thickness of the molten layer was also increased. The initial equiaxed grains changes to quite elongated grains shape. The surfaces were structured under α″ martensite, α and matrix β. The β phase content decreased slightly and the α″ phase increased for both alloys increasing the laser conditions. The condition A increased the elastic modulus (E) and decreased the hardness while condition B did not affect the mechanical properties surface for the TNT system compared to base metal (BM). In TNS system the laser condition A decreased the E and increased the hardness while increasing the laser parameters (Condition B) both E and hardness decreased compared to BM. The laser surface treatment was influenced by the levels of alloying elements present promoting most significant changes in the microstructure and mechanical properties in the TNS system.