Oxygen boost diffusion of additively manufactured Ti-6Al-4V for improved oxide layer adhesion

The advancement of additive manufacturing (AM) for Ti-6Al-4V has broadened its application, particularly in the biomedical field, where patient-specific implants with complex geometries, previously unattainable via traditional manufacturing, are now feasible. However, untreated Ti-6Al-4V is known to exhibit poor wear performance. To address this, post-processing treatments such as boost diffusion, which involves oxygen diffusion to induce gradual case hardening, followed by thermal oxidation to form a hard, wear-resistant oxide layer, have shown promise in enhancing the wear properties of AM Ti-6Al-4V. This study investigates boost diffusion treatment to optimise the formation of an adherent oxide layer on AM Ti-6Al-4V, while also examining the impact of the starting microstructure on treatment efficacy. The optimised boost diffusion process resulted in an oxygen diffusion depth of 215 mu m and hardness values up to three times higher than the bulk material, particularly at the oxide layer/metal substrate interface. The adhesion of the oxide layer was rated as class one.