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This study investigated the impact of low-temperature heat treatments on the mechanical and thermophysical properties of Cu-10Sn alloys fabricated by a laser powder bed fusion (LPBF) additive manufacturing (AM) process. The microstructure, phase structure, and mechanical and thermal properties of the LPBF Cu-10Sn samples were comparatively investigated under both the as-fabricated (AF) condition and after low-temperature heat treatments at 140, 180, 220, 260, and 300 °C. The results showed that the low-temperature heat treatments did not significantly affect the phase and grain structures of the Cu-10Sn alloys. Both pre- and post-treatment samples displayed consistent grain sizes, with no obvious X-ray diffraction angle shift for the α phase, indicating that atom diffusion of the Sn element is beyond the detection resolution of X-ray diffractometers (XRD). However, the 180 °C heat-treated sample exhibited the highest hardness, while the AF samples had the lowest hardness, which was most likely due to the generation of precipitates according to thermodynamics modeling. Heat-treated samples also displayed higher thermal diffusivity values than their AF counterpart. The AF sample had the longest lifetime of ~0.19 nanoseconds (ns) in the positron annihilation lifetime spectroscopy (PALS) test, indicating the presence of the most atomic-level defects.
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This content will become publicly available on June 11, 2026
Influence of In Situ and Ex Situ Heat Treatments on the Mechanical Behavior of LPBF-Fabricated Fe–Mn–Al–Ni Shape Memory Alloys
Abstract This study investigates the fabrication of Fe–Mn–Al–Ni iron-based shape memory alloys (SMAs) using laser powder bed fusion (LPBF) across a range of laser powers. The influence of energy input on material properties was assessed by evaluating the resulting volumetric energy density. Samples were produced under both as-built conditions and subjected to in situ and ex situ treatments to enhance performance. Mechanical properties were characterized through macro-indentation, Profilometry-based Indentation Plastometry (PIP), and nanoindentation techniques, while room-temperature compression testing was conducted to assess superelastic behavior. Microstructural and phase variations were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that increasing the fabrication power improved the mechanical properties of the as-built SMAs, with the optimal performance achieved at 175 W. In situ/ex situ treatments led to a significant reduction in strength but enhanced ductility by up to 39%, along with a 52% reduction in microhardness for samples fabricated at 175 W. Overall, the LPBF-produced Fe–Mn–Al–Ni SMAs exhibited good strain recovery and stability, comparable to those produced by conventional methods. This work demonstrates the potential of LPBF in developing Fe–Mn–Al–Ni SMAs with properties matching traditionally manufactured counterparts. Graphical Abstract Mechanical behavior and microstructural features of LPBF-fabricated Fe–Mn–Al–Ni SMA under the effects of in situ and ex situ treatments
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- Award ID(s):
- 2301766
- PAR ID:
- 10617116
- Publisher / Repository:
- Springer
- Date Published:
- Journal Name:
- Shape Memory and Superelasticity
- ISSN:
- 2199-384X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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