FEC - School of Mechanical & Manufacturing Engineering
School of Mechanical & Manufacturing Engineering
Novel Insights into Laser-Powder-Bed-Fused NiTi Alloys for Improved Wear Resistance

Novel Insights into Laser-Powder-Bed-Fused NiTi Alloys for Improved Wear Resistance

A recent study from I-Form, the SFI Research Centre for Advanced Manufacturing and the Advanced Processing Technology Research Centre at Dublin City University, has shed important light on how subtle shifts in nickel content can markedly influence the mechanical and tribological behaviour of nickel-titanium (NiTi) alloys produced via laser powder bed fusion (PBF-LB). The team fabricated two distinct compositional variants, Ni 51.1 Ti 48.9 and Ni 49.8 Ti 50.2 (at. %), and conducted a thorough investigation of their microstructure, microhardness, nano-scale mechanical properties, and wear performance under reciprocating conditions.

The Ni 49.8 Ti 50.2 alloy exhibited refined microstructural characteristics, including fine equiaxed grains interspersed with columnar dendrites, in contrast to the slightly coarser equiaxed cells of the higher-nickel alloy. This more uniform structure translated into greater microhardness and nanohardness. Although the higher-nickel variant demonstrated a marginally lower coefficient of friction, 0.72 versus 0.76 for the lower-nickel alloy, the Ni 49.8 Ti 50.2 alloy achieved superior wear resistance.

Wear resistance was found to be strongly correlated with factors such as the hardness-to-elastic-modulus ratio (H/E), strain-hardening capacity, and the formation of stable tribolayers along the wear track. These tribolayers, largely absent in the Ni 51.1 Ti 48.9 alloy, played a key role in mitigating wear. Based on these findings, the lower-nickel composition (Ni 49.8 Ti 50.2) emerges as a better candidate for heavy-duty tribological interfaces, offering a compelling combination of microstructural integrity and wear resilience.

This research marks a significant step forward in refining additive manufacturing strategies for NiTi alloys, particularly in applications where surface wear and durability are critical. By pinpointing the influence of nickel concentration on microstructure and wear behaviour, the work provides a clear pathway towards optimising NiTi components produced via PBF-LB, especially for use in demanding industrial or biomedical environments.

Read the full paper: Influence of nickel concentration on multi-scale mechanical properties and wear behavior of NiTi alloys processed via laser powder bed fusion, Applied Surface Science Advances, here.