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Dela Cruz et al. Microstructures 2023;3:2023012 Microstructures
DOI: 10.20517/microstructures.2022.33

Research Article Open Access

Microstructure evolution in laser powder bed fusion-

built Fe-Mn-Si shape memory alloy

2
1
Michael Leo Dela Cruz , Vladislav Yakubov , Xiaopeng Li 2 , Michael Ferry 1
1
School of Material Science and Engineering, University of New South Wales, Sydney 2052, Australia.
2
School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney 2052, Australia.
Correspondence to: Prof. Michael Ferry, School of Material Science and Engineering, University of New South Wales, Sydney
2052, Australia. E-mail: m.ferry@unsw.edu.au; Dr. Xiaopeng Li, School of Mechanical and Manufacturing Engineering, University
of New South Wales, Sydney 2052, Australia. E-mail: xiaopeng.li@unsw.edu.au
How to cite this article: Dela Cruz ML, Yakubov V, Li X, Ferry M. Microstructure evolution in laser powder bed fusion-built Fe-
Mn-Si shape memory alloy. Microstructures 2023;3:2023012. https://dx.doi.org/10.20517/microstructures.2022.33

Received: 4 Oct 2022 First Decision: 3 Nov 2022 Revised: 14 Dec 2022 Accepted: 19 Jan 2023 Published: 14 Feb 2023
Academic Editor: Ting Zhu Copy Editor: Fangling Lan Production Editor: Fangling Lan

Abstract
The need for specialty powder composition limits the processing of a wide range of alloy products via the laser
powder bed fusion (LPBF) technique. This work extends the adaptability of the LPBF technique by fabricating the
first-ever Fe-30Mn-6Si (wt.%) product for potential use as a biodegradable shape memory alloy (SMA). Different
LPBF processing parameters were assessed by varying the laser power, scan speed, and the laser re-scan strategy
to achieve a fully dense part. The microstructure was found to respond to the processing conditions. For example,
the microstructure of the parts produced by the high linear energy density (LED) had a columnar and strong
crystallographic texture, while in the low LED, the parts were almost equiaxed and had a weak texture. To explain
the evolved microstructure, the thermal history of the LPBF products was computed using the finite element
analysis (FEA) of the melt pool gathered from a single-track laser scan experiment. The FEA results showed a
varying temperature gradient, cooling and solidification rates, and temperature profile as a function of LED. Then,
the relationship of hardness between grain size, phases present, and crystallographic misorientation of the LPBF-
built alloy was analysed with reference to a control alloy of similar composition but prepared by arc melting. This
study validates the LPBF processability of Fe-Mn-Si SMA and provides a new insight into the influence of
processing parameters on the formed microstructure and hardness.

Keywords: Laser powder bed fusion, microstructures, biodegradable, shape memory alloy, Fe-Mn, Fe-Mn-Si, EBSD

© The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0
International License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, sharing,
adaptation, distribution and reproduction in any medium or format, for any purpose, even commercially, as
long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and
indicate if changes were made.

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