Enhanced mechanical and damping properties of Cu-Modified Al-Ni eutectic alloys: Solid-solution and precipitation...

The study aimed to analyze the mechanical properties, precipitation strengthening, and microstructure of Al-Ni-Cu alloys to understand their enhanced characteristics. Additionally, the damping behavior was examined using a dynamic mechanical analyzer across a continuous heating temperature range with frequencies from 0.5 to 15 Hz. The experimental results indicate that the Al-Ni eutectic alloy, which exhibits an ultrafine Al₃Ni intermetallic fiber-reinforced Al matrix, transitions to a dendritic-ultrafine eutectic composite structure. The Cu-containing alloys exhibit two distinct primary phases: α-Al and Al-Ni-Cu ternary intermetallic compounds. The eutectic matrix transforms from Al-Al₃Ni to Al-Al₇Cu₄Ni, and subsequently to Al-Al₂Cu. These microstructural evolutions result in an enhancement of the tensile yield strength from 170 MPa to 440 MPa, with additional hardening achieved through aging-induced precipitation. Moreover, the damping capacity improves with the addition of Cu at elevated temperatures, and there is an increase in frequency dependence. This paper will discuss the microstructural features, mechanical properties, deformation behaviors, and damping properties in detail.