Heat Treatment Improves the Strength–Ductility Balance of 3D-Printed Aluminum Bronze for Cooling Systems in Electronic Components Operating Under Extreme Conditions

Researchers from Skoltech (part of VEB.RF Group), together with colleagues from Saint Petersburg State Marine Technical University and other research organizations, have developed an approach that improves the combination of strength and ductility in aluminum bronze components manufactured by 3D printing.

The findings expand the potential of additive manufacturing for producing heat exchangers and other cooling system components used in electronic devices operating under high mechanical and thermal loads. The study was published in the Journal of Alloys and Compounds.

"A heat exchanger is a device that removes heat from a processor or other heat-generating components. To perform this function effectively, it must be made of a material with high thermal conductivity and have an optimized geometry," explains the study's lead author, Anastasia Filippova, a PhD student in Skoltech's Mathematics and Mechanics program. "3D-printed aluminum bronze offers a favorable combination of thermal performance and geometric design flexibility. However, the printing process itself can result in suboptimal mechanical properties. This is particularly important for electronics used in rockets and other systems exposed to shock and vibration, as well as repeated thermal and mechanical loading."

Aluminum bronze is a copper alloy containing aluminum and a small amount of iron. Compared with pure copper, this material is better suited for 3D printing because it reflects less laser radiation and exhibits greater mechanical stability. At the same time, the rapid solidification of the metal during additive manufacturing can lead to chemical heterogeneity and the formation of a non-equilibrium microstructure, adversely affecting the performance of the finished components.

After examining the samples using scanning electron microscopy, the researchers confirmed the presence of such structural heterogeneities and hypothesized that they could be eliminated through post-process heat treatment.

"However, materials produced by 3D printing always differ somewhat in microstructure from the same alloy manufactured by conventional methods. Therefore, there is no guarantee that a well-established approach such as heat treatment will produce the desired effect. In fact, it may even degrade the material's properties. Alternatively, the heat treatment parameters may require careful optimization—which is exactly what we found in our study," says the project's principal investigator, Stanislav Evlashin, Associate Professor at Skoltech's Center for Materials Technologies.

Because no standard heat treatment regimes had previously been established for additively manufactured aluminum bronze, the researchers investigated three different heat treatment conditions. The samples were held in an electric furnace at 300°C, 400°C, and 500°C for three hours, after which their properties were compared with those of the as-printed material.

The study showed that heat treatment at 300°C and 400°C promoted the formation of non-equilibrium phases that reduced the material's ductility. The most effective treatment was heating to 500°C, which reduced chemical heterogeneity, promoted the formation of a more stable microstructure, and achieved the best balance between strength and ductility.

These findings could contribute to the development of more reliable heat exchangers and other cooling system components for high-performance electronics used in aerospace, transportation, and other high-tech industries.

Image credit: Anastasia Filippova et al.Journal of Alloys and Compounds

Source: Skolkovo Institute of Science and Technology (Skoltech)