A single parameter approach to enhance the microstructural and mechanical properties of beta Ti-Nb alloy via open-air fiber laser nitriding

Abstract

A single parameter approach to enhance the microstructural and mechanical properties of beta Ti-Nb alloy via open-air fiber laser nitriding.

Optimization of anti-wear and anti-bacterial properties of beta TiNb alloy via controlling duty cycle in open-air laser nitriding

“…When the laser tracks significantly overlapped, they tended to "crush" with each other and thus produce "peaks" where the roughest regions can be recognized on the surfaces of DC80 and DC100. A detailed explanation to the structure of the fully-covered samples, namely DC40 to DC100 had been reported elsewhere (Chan et al, 2020).The findings indicated that minimum overlapping between the laser tracks would give desirable results to obtain the crack-free surface.…”

“…In this study, we have reproduced the formation of laser-nitride layer on beta TiNb surface by open-air laser-nitriding as in the previous study (Chan et al, 2020), but with an extended range of the duty cycles from 5% (modulated mode) to 100% (continuous wave, CW mode). More importantly, the present study focuses on the characterization of functional properties, in particular anti-wear and anti-bacterial properties of laser-nitrided TiNb surfaces.…”

“…The same image processing for DC40 to DC100 showed all white and indistinguishable images (not shown), suggesting a full coverage of laser tracks for these samples. In fact, analysis of images for DC40 to DC100 by another mode of ImageJ showed increasing overlapping areas between the laser tracks with increasing duty cycle from 5.4%(DC40) to 24.8% (DC100) (Chan et al, 2020). at the duty cycles of 20% and higher showed higher Sz values than BM.…”

“…Briefly, remelted pool with semicircular shape started to become apparent from DC40, and the depth of re-melted pool increased with increasing DC; the thickness of the re-melted pool was determined from 22 m (DC40) to 43 m (DC100) (Chan et al, 2020). A trace of this microstructural feature is also visible from DC20, yet it is missing in DC5.…”

“…This approach has been very effective to create surface hardening of various types of Ti-based alloys (Katayama et al, 1983). Recently, the authors have shown that this approach can be applicable to TiNb surfaces too (Chan et al, 2020). The gold-coloured TiN layers formed by the open-air laser nitriding method in modulation of duty cycle generated a range of TiN layer with varying thickness (22-43µm) and hardness (reaching to 870HV).…”