Development and characterization of Al–Li alloys

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 420; no. 1-2; pp. 228 - 234
• Main Authors: Gupta, R.K., Nayan, Niraj, Nagasireesha, G., Sharma, S.C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25-03-2006; Elsevier
• Subjects: Aircraft industry. Spacecraft; Al–Li alloy; Applications; Applied sciences; Casting; Engineering techniques in metallurgy. Applications. Other aspects; Exact sciences and technology; Homogenization; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Precipitation; Homogenization; Casting; Precipitation; Al–Li alloy; Scanning electron microscopy; Heat treatment; Ageing; Mechanical properties; Al-Li alloy; Aluminium alloy; Aeronautic industry; Fabrication property relation; Thickness; Forging; Solution heat treatment; Optical microscopy; Tempering; Hot rolling; Lithium alloy
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2006.01.045

Increased strength to weight ratio of aluminium–lithium alloys has attracted material scientists to develop these for aerospace applications. But commercial scale production of these alloys has always been slow in view of difficulties encountered during addition of lithium and in ensuring homogeneous billet composition. A new technique of Li addition has been adapted, which gives maximum recovery of Li in the billet. Using this technique, aluminium–lithium alloys of two different grades for aerospace application were cast. Billets were hot forged and rolled to the thickness range of 3–4mm and heat-treated for different temper conditions. Mechanical properties were evaluated in T6 (solution treated and artificial aged), T8 (solution treated, cold worked and artificial aged) and T4 (solution treated and natural aged) temper conditions. Both alloys exhibit a strong natural aging response. Reversion for short periods at 180°C results in decrease of strength. With artificial reaging strength reaches above the T4 temper condition level. Characterization was carried out using optical microscope (OM) and scanning electron microscope (SEM). Experimental investigation shows that addition of lithium at high melt temperature gives lower recovery of Li, and use of impure aluminium adversely affects the mechanical properties of the alloy in all temper conditions.