Improved Versatility of High Damping Composites Obtained From Cu-Al-Ni SMA Powders

In the last decades, issues on absorption of vibration energy have attracted much attention in several technological sectors like vibration isolation in high-precision electronics, building protection in civil engineering, etc.. In the past, mainly polymers were used as high-damping materials, but the increasingly demanding working conditions (e.g. high service temperature) have encouraged the scientific community to look for alternative materials. High-damping metallic materials and, in particular, metal matrix composites were proposed as a feasible solution. Among them, shape memory alloys (SMA) intrinsically show very high damping properties, thanks to dissipative movements of the interfaces generated during their characteristic martensitic transformation, which have already found some practical damping applications. Taking advantage of both the high-damping capacity of Cu-Al-Ni SMAs and the flexibility of composite production, very high-damping metal matrix composites were developed (San Juan & Nó, 2006, Mat. Sci. Eng. A, 442, 429-432; López et al., 2009, J. Mater. Eng. Perform. 18, 459-462) and patented.

New advances reached in this research line are introduced in the present contribution. By combining Cu-Al-Ni SMA powders with different compositions and using other Sn-In matrices, which also exhibit a martensitic transformation, the temperature range where the composites show very high damping capacity can be broadened significantly.

Phase transformations and damping behavior of Cu-Al-Ni particles and Sn-In matrices, as well as the composites, have been studied by DSC and mechanical spectroscopy. From the comparison of such measurements we have obtained valuable information about the synergy effects contributing to increase the damping and the mechanical properties, leading to an improvement of the merit index for structural damping.