Effect of the Addition of High Li Concentration on the Microstructure and Mechanical Properties of Al–Mg–Si Alloys with Different Mg Contents

In the present work, microstructural characteristics and mechanical properties of Al–1.5 Mg–0.6Si Al–3.0 alloy containing 3 wt% Li were investigated by optical microscopy (OM), X-ray diffraction analysis (XRD), scanning electron (SEM), time flight–secondary ion mass spectrometry (SIMS), transmission (TEM), performance testing. The addition reduces density base up to 8.4%. residual second phases contain Mg Si in hot-rolled condition, but Mg/Si atomic ratio decreases after quenching, which means that substitute some convert Mg2Si into a (Mg, Li)2Si phase during solution treatment. results SIMS observations confirm this. high Mg-containing has more rapid hardening response compared low alloy. TEM observation reveals δ′-Al3Li + β′′-Mg2Si dual can be observed aging for 100 h at 170 °C. higher content enhances precipitation δ′ phase, having larger average diameter size particles wider δ′-precipitate-free zones (δ′-PFZs). are significantly improved with elastic modulus increasing than 16.5%. However, existence large wide δ′-PFZs Li-containing alloys is detrimental their ductility; as result, elongation much lower