Effect of Co additions on the damping properties of Cu–Al–Ni shape memory alloys

• Published in: Journal of alloys and compounds 2020-12, Vol.847, p.156560, Article 156560
• Main Authors: Chang, Shih-Hang, Liao, Bo-Siang, Gholami-Kermanshahi, Mozhgan
• Format: Article
• Language: English
• Subjects: Copper; Damping; Dynamic mechanical analysis; Grain boundaries; Grain size; Heat treating; Internal friction; Martensite; Martensitic transformation; Martensitic transformations; Nickel; Precipitates; Shape memory alloys; Shape memory alloys (SMAs); Twin boundaries
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.156560

This study investigates the effect of Co additions on the damping properties of Cu-13.5Al–4Ni-xCo and Cu-14.0Al–4Ni-xCo (x = 0–2 wt%) shape memory alloys (SMAs). The Cu-14.0Al–4Ni SMA exhibits a higher inherent and intrinsic internal friction (IFPT + IFI) peak than the Cu-13.5Al–4Ni SMA, but its (IFPT + IFI) peak temperature is below 0 °C. Adding Co into the Cu-14.0Al–4Ni SMA can effectively increase the (IFPT + IFI) peak temperature and reduce the grain size of the alloys. The grain size of the Cu-14.0Al–4Ni-xCo SMAs decreases from approximately 300 μm to below 50 μm when the Co content increases from 0 to 2 wt%. The (IFPT + IFI) peak temperature for the Cu-14.0Al–4Ni-xCo SMAs increases from −0.1 °C to 77.7 °C when the Co content increases from 0 to 1 wt%, but their tan δ values decrease from 0.0402 to 0.0090 simultaneously. The Cu-14.0Al–4Ni–2Co SMA does not exhibit an observable (IFPT + IFI) peak. The tan δ values of the (IFPT + IFI) peaks decrease with increasing Co content because the movements of the parent/martensite phase interfaces and twin boundaries are impeded by the increased amounts of grain boundaries and γ2 phase precipitates. Among these Cu–Al–Ni–Co SMAs, the Cu-14.0Al–4Ni-0.5Co SMA is more suitable for high-damping applications as it possesses an (IFPT + IFI) peak with tan δ close to 0.02 at approximately 50 °C. •Adding Co into Cu–Al–Ni SMAs can increase the (IFPT + IFI) peak temperature.•Adding Co into Cu–Al–Ni SMAs can reduce the grain size of the alloys.•The tan δ values of Cu–Al–Ni–Co SMAs decrease with increasing Co content.•Cu-14.0Al–4Ni-0.5Co possesses an (IFPT + IFI) peak with tan δ close to 0.02 at 50°C.