Tailoring the superelastic properties of an additively manufactured Cu–Al–Mn shape memory alloy via adjusting the scanning strategy

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2023-01, Vol.862, p.144412, Article 144412
• Main Authors: Babacan, N., Pilz, S., Pauly, S., Hufenbach, J., Gustmann, T.
• Format: Article
• Language: English
• Subjects: Additive manufacturing; Aluminum; Copper; Copper base alloys; Cu-based shape memory alloy; Cu–Al–Mn; Electron backscatter diffraction; Grain size; Laser powder bed fusion; Manganese; Martensitic transformations; Microstructure; Misalignment; Porosity; Powder beds; Recoverable strain; Rotation; Scanning; Scanning strategy; Shape memory alloys; Superelasticity; Texture; Transformation temperature
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2022.144412

The effects of the scan vector rotation angle in adjacent layers during laser powder bed fusion of a Cu71.6Al17Mn11.4 (at.%) shape memory alloy on the porosity, microstructure, transformation temperatures, as well as superelastic properties, were investigated. To explore the influence of the applied scanning strategy, a bidirectional stripe hatching was employed by utilizing 0°, 25°, 50°, 79° and 90° rotation of the scanning direction in adjacent layers. Changing the scan vector rotation had no apparent effect on the characteristics of porosity. The scan vector rotation allowed a manipulation of the microstructure (grain size, texture) to some extent which was evaluated via electron backscattered diffraction (EBSD) analysis. While the size and distribution of grains only showed negligible differences, a more pronounced change in the texture as well as in the grain misorientation has been observed. A significant recoverable strain difference for the applied scan vector rotations was observed as a result of compressive loading-unloading tests. The samples produced with 90° scan vector rotation exhibited 6.05% recoverable strain under 8% applied strain, whereas only minor recoverable strain values (around 1.4%) were obtained in the specimens produced without a shift in the scan vector rotation (0°). Other vector rotations (25°, 50°, 79°) resulted in a moderate superelastic performance with respect to the 90°-samples. These findings clearly show that polycrystalline Cu–Al–Mn shape memory parts with high shape-recovery rates can be directly fabricated using laser powder bed fusion and an adjusted scanning strategy. Thus, this approach can serve as a general tool to optimize or control superelasticity in additively manufactured Cu-based SMAs. •Different scan vector rotation angles during laser powder bed fusion were used to process a Cu–Al–Mn shape memory alloy.•The superelasticity can be directly tailored during fabrication via adjusting the scan vector rotation.•A significant improvement of superelasticity via adjusting the scan vector rotation was obtained.•LPBF samples produced with 90° scan vector rotation exhibited 6.05% recoverable strain under 8% applied compressive strain.