Outstanding strengthening behavior and dynamic mechanical properties of in-situ Al–Al3Ni composites by Cu addition

Abstract

The microstructure, mechanical properties, and dynamic mechanical properties of the various intermetallic-reinforced in-situ Al–Al3Ni eutectic composites were investigated for different compositions with increasing Cu content. The microstructure changes from a nanofiber-like Al3Ni-reinforced composite structure to a various intermetallic-reinforced composite structure. Moreover, the addition of Cu induces changes in the phases composing the composite, especially the kind of intermetallic compounds, such as Al3Ni, Al3NiCu, Al7Ni4Cu, and Al2Cu. According to these microstructural evolutions, the mechanical strength under compressive loading is drastically enhanced from about 200 to 1200 MPa, and a typical strength-ductility tradeoff, e.g., the plasticity is reduced from more than 70% to less than 2% with the strength increase, is also observed. The precipitation behavior which can lead to improving further strengthening was observed employing in-situ TEM, Vickers hardness, and DSC investigations. The damping properties are also improved with increasing Cu content, especially at high-temperatures; but regrettably, the maximum operating temperature is decreased. We will discuss the origin of the enhanced strength and propose a route to obtain composites with optimized mechanical and damping properties for application in different fields.