# Effects of Ultrasonic Nanocrystal Surface Modification on the Formation of a Nitride Layer in Ti-6Al-4V Alloy

## TL;DR

This study shows that ultrasonic treatment improves the formation of nitride layers on titanium alloy surfaces, enhancing hardness and wear resistance for biomedical and engineering applications.

## Contribution

The novel contribution is demonstrating how optimized ultrasonic nanocrystalline surface modification enhances nitride layer formation and mechanical properties in Ti-6Al-4V alloy.

## Key findings

- Optimized ultrasonic treatment increases surface hardness by up to 25% and elastic modulus by up to 18%.
- High-load and elevated-temperature ultrasonic treatment leads to dense TiN/Ti2N layers with improved wear resistance.
- SEM and XRD analyses confirm microstructural densification and increased nitride phase intensity.

## Abstract

This study investigates the effects of ultrasonic nanocrystalline surface modification (UNSM) on the formation of nitride layers in Ti-6Al-4V alloy during ion-plasma nitriding (IPN). Various UNSM parameters, including vibration amplitude, static load, and processing temperature, were systematically varied to evaluate their influence on microstructure, hardness, elastic modulus, and tribological behavior. The results reveal that pre-treatment with optimized UNSM conditions significantly enhances nitrogen diffusion, leading to the formation of dense and uniform TiN/Ti2N layers. Samples pre-treated under high-load and elevated-temperature UNSM exhibited the greatest improvements in surface hardness (up to 25%), elastic modulus (up to 18%), and wear resistance, with a reduced and stabilized friction coefficient (~0.55). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses confirmed microstructural densification, grain refinement, and increased nitride phase intensity. These findings demonstrate not only the scientific relevance but also the practical potential of UNSM as an effective surface activation technique. The hybrid UNSM + IPN approach may serve as a promising method for extending the service life of load-bearing biomedical implants and engineering components subjected to intensive wear.