Influence of rapid solidification and lithium additions on microstructure and mechanical properties of aluminum based alloys

Abstract

A series of aluminum-lithium or lightweight alloys containing up to 5 wt. % lithium was rapidly solidified from melt by chillblock melt-spun technique. The resultant ribbons were studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and deferential scanning calorimetry (DSC) techniques. The results showed that the structures of all melt-spun ribbons were completely composed of two distinct phases aluminum rich phase and intermetallic compound (IMC) Al9.8- Li1.1phase. It is also found that melting point, solidus and liquidus temperatures of the lightweight alloys are lowered as the Li content is increased. Additionally, elastic moduli, internal friction, thermal diffusivity and hardness measurements of melt-spun ribbons were examined by using dynamic resonance method and Vickers indenter for one applied load of 25 grams of force for 5, 20, 40, 60, 80 and 99 seconds. Results interpreted in terms of the phase changes occurring in the alloy system. With the addition of Li, the Al rich phase is finer in grain size, and intermetallic compound is more uniformly distributed. As a result, Young's modulus and micro-hardness of Lightweight are increased when Li is added into the Al
alloy. The aim of the research planned in this work was to design the A1-Li family of alloys contribute to their increasingly broad application in aeronautics, as an alternative for the aluminum alloys, which have been used so far.