Laser Powder Bed Fusion of Cu-Al-Ni-Mn Shape-Memory Alloy for the Application of Active Heat Sinks: Processability, Microstructures, and Shape-Memory Effect

Cu-based shape-memory alloys (Cu-based SMAs) demonstrate prospects in active heat sinks due to their excellent thermal conductivity, high transformation temperature, and low cost. However, their inferior mechanical properties have hindered their industrial application. Previous studies have indicated that mechanical properties can be improved by decreasing grain size and minimizing microstructural segregation, which can be achieved by laser powder bed fusion (LPBF) process. This work investigates the influence of process parameters on the processability, microstructure, and shape-memory effect (SME) of 81.95Cu-11.85Al-3.2Ni-3Mn (wt%) thin-walled samples fabricated by LPBF. Results reveal that laser power and scanning speed significantly affect the relative density of the Cu-based SMA thin-walled samples, and higher laser power and scanning speed contribute to better processability. Additionally, the high cooling rate during the LPBF process facilitates the formation of beta 1 ' martensite without requiring posttreatment, and the size of the beta 1 ' martensite decreases with increasing scanning speed. In bending-recovery experiments, specimens fabricated at higher scanning speed exhibit the highest SME recovery rate and bending angle. Moreover, the test confirms that Cu-based SMA formed at lower scanning speeds exhibits even higher thermal conductivity. This work shows the potential of fabricating high-performance Cu-based SMA components by LPBF. Higher laser power and scanning speed contribute to better processability of the Cu-based shape-memory alloy (SMA) thin-walled samples. The high cooling rate during the laser powder bed fusion process facilitates the formation of beta 1 ' martensite. Forming Cu-based SMA at higher scanning speeds results in smaller beta 1 ' martensite sizes, the highest shape-memory effect recovery rate, and the highest bending angles.image (c) 2023 WILEY-VCH GmbH