Ultra-lightweight alloys with high strength, ductility and corrosion resistance are desirable for applications in the automotive, aerospace, defence, biomedical, sporting and electronic goods sectors. Ductility and corrosion resistance are generally inversely correlated with strength, making it difficult to optimize all three simultaneously. Here we design an ultralow density (1.4 g cm(-3)) Mg-Li-based alloy that is strong, ductile, and more corrosion resistant than Mg-based alloys reported so far. The alloy is Li-rich and a solute nanostructure within a body-centred cubic matrix is achieved by a series of extrusion, heat-treatment and rolling processes. Corrosion resistance from the environment is believed to occur by a uniform lithium carbonate film in which surface coverage is much greater than in traditional hexagonal close-packed Mg-based alloys, explaining the superior corrosion resistance of the alloy.

calculated from the oxidation potential versus the internal standard of ferrocene/ferrocenium and the I p (5.43 eV) so obtained for PATPD was in good agreement with the I p reported for TPD based materials (5.4 eV determined by UV-PES) [26].Absorption Spectra: Absorption spectra of the samples were measured with a Cary 5G spectrophotometer.Dark Conductivity and Photoconductivity: Steady-state conductivity properties were determined in the dark. To measure the steadystate dark conductivity, an electric field (E a ) was applied and the current (i dark ) was measured. To assure steady-state conditions a dwell time of 15 s between each reading was used. The applied electric field was swept from 0 to 76 V lm ±1 over a period of 7 min. The current was measured using a Keithley 6517A electrometer.Four-Wave Mixing and Exposure Dependent Transient Four-Wave Mixing Experiments: A detailed discussion about the experimental set-up is given in [22].