AccScience Publishing / ESAM / Online First / DOI: 10.36922/ESAM025340020
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ORIGINAL RESEARCH ARTICLE

Effect of build distribution and particle properties on the physical characteristics of laser powder bed fusion of in situ alloyed nitinol

Declan Bourke1,2,3,4* ,  Medad C.C. Monu2,3,4 ,  Paul Healy1 ,  Alexander Sloane5 ,  Inam Ul Ahad2,3,4 ,  Dermot Brabazon2,3,4
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1 Department of Product Development, Fort Wayne Metals Ireland, County Mayo, Connacht, Ireland
2 I-Form, the SFI Research Centre for Advanced Manufacturing, Dublin City University, Dublin, Ireland
3 School of Mechanical and Manufacturing Engineering, Faculty of Engineering and Computing, Dublin City University, Dublin, Ireland
4 DCU Institute for Advanced Processing Technology, Dublin City University, Dublin, Ireland
5 School of Chemical, Materials and Biological Engineering, Faculty of Engineering, University of Sheffield, Yorkshire, United Kingdom
ESAM 2025, 1(3), 025340020 https://doi.org/10.36922/ESAM025340020
Received: 5 August 2025 | Revised: 22 August 2025 | Accepted: 28 August 2025 | Published online: 18 September 2025
© 2025 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
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Abstract

The impact of powder flow characteristics on in situ nickel (Ni)-titanium (Ti) alloy formation within the laser powder bed fusion (LPBF) process is poorly understood. In this study, flow segregation patterns of Ni-Ti powder blends within the LPBF build chamber were examined and were found to be influenced by the substrate surface, build layout distribution, and particle size distribution. These segregation patterns significantly impacted relative density (RD) and elasto-caloric properties of in situ alloyed nitinol components, with regions of lower RD correlated with lower Ni content and higher phase transformation enthalpies than regions with higher Ni content. It was found that powder segregation rates between Ti and Ni particles were higher for rougher substrates, which also contained higher amounts of unmelted powder than smoother substrates. Furthermore, the position of the unmelted powder relative to the deposition arm sweep impacted powder segregation patterns throughout the build chamber. Powder segregation patterns in the LPBF deposition bed were also affected by differences in material density between Ni and Ti and interparticle cohesive forces. The insights gained from this work provide a route to achieving improved microstructural and chemical homogeneity of in situ alloyed nitinol, with tailored thermo-mechanical performance.

Graphical abstract
Keywords
Nitinol
Additive manufacturing
Laser powder bed fusion
In situ alloying
Funding
This publication has emanated from research supported by a research grant from the Science Foundation Ireland (SFI) under grant number 16/RC/3872 and is co-funded by I-Form industry partner Fort Wayne Metals Ireland.
Conflict of interest
The authors declare that they have no competing interests.
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Engineering Science in Additive Manufacturing, Electronic ISSN: 3082-849X Published by AccScience Publishing
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