Effect of interference laser treatment on the surface region homogeneity of a biomedical ?-Ti alloy

This study provides a detailed insight into the microstructure and chemical composition of a surface region of a novel, metastable Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy with a low Young's modulus modified by Direct Laser Interference Patterning (DLIP) using an Nd:YAG (1064 nm) with 10 ns pulse duration. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy, and Scanning Transmission Electron Microscopy (STEM) were employed to investigate the microstructure of the cross-section of modified TNTZ. For chemical compo-sition analysis of the surface region, X-ray Photoelectron Spectroscopy (XPS) and Atom Probe Tomography (APT) were applied. The chemical composition analysis was divided into two stages: surface analysis (XPS and APT) and analysis of a bulk (APT at the depth of 300 nm). Through the interference phenomenon during DLIP treatment, we observed significant microstructure evolution in the surface region of TNTZ alloy - grain refinement on the tops of the grooves while the microstructure at the bottoms was unattached. APT measurements at the depth of 300 nm revealed a noticeable local chemical heterogeneity of the substrate alloy, that has not been considered before when designing the metastable-Ti6 systems. The applied laser treatment homogenizes the remelted zones and thus provides an additional factor influencing the surface properties.

Automated summary

This study investigates the microstructure and chemical composition of a novel metastable TNTZ alloy modified by DLIP using a Nd:YAG laser. SEM, TEM, and STEM were used to analyze the microstructure, while XPS and APT were employed for chemical composition analysis. The study reveals significant microstructure evolution in the TNTZ alloy surface region due to DLIP treatment, along with local chemical heterogeneity of the alloy that was not considered before in design. The laser treatment homogenizes the remelted zones and influences surface properties.