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].

The piezoresistive behavior of a silicon carbonitride ceramic derived from a polymer precursor is investigated under a uniaxial compressive loading condition. The electric conductivity has been measured as a function of the applied stress along both longitudinal and transverse directions. The gauge factor of the materials was then calculated from the data at different stress levels. The results show that the material exhibits an extremely high piezoresistive coefficient along both directions, ranging from 1000 to 4000, which are much higher than any existing ceramic material. The results also reveal that the gauge factor decreases significantly with increasing applied stress. A theoretical model based on the tunneling–percolation mechanism has been developed to explain the stress dependence of the gauge factor. The unique piezoresistive behavior is attributed to the unique self‐assembled nanodomain structure of the material.

Commercially available polyureamethylvinylsilazane (Ceraset, Kion Corporation, Huntington Valley, PA) and aluminum isopropoxide (Al(OCH(CH 3 ) 2 ) 3 ) (AIs, Alfa Aesar, Ward Hill, MA) were used as starting materials. Ceraset, as received, is a pale yellow liquid, and AIs is a white powder. Both materials were used as received without further purification. Figure 1 shows the chemical structure of Ceraset cited by the supplier 24-27 and confirmed by previous study. 28 The polyaluminasilazanes were prepared using the following procedure. First, AIs powders were dissolved in liquid Ceraset at room temperature while stirring magnetically. A small amount 2415 J ournal

The electric conductivity of polymer-derived silicon carbonitrides made from a polysilazane modified with different amounts of thermal initiator is measured at room temperature. It is found that the thermal initiator has a significant effect on the electric conductivity, which first increases and then decreases with increasing thermal initiator concentration. The highly conductive sample exhibits a very high piezoresistive coefficient and weak temperature dependence as compared with the low conductive samples. The microstructures of the materials are characterized using a Raman spectroscope. Based on these results, two conducting mechanisms are identified: the highly conductive sample is dominated by the tunneling-percolation mechanism, while the low conductive samples are dominated by matrix phases. The effect of the thermal initiator on the development of the microstructures of the materials is discussed.

Strengthening of magnesium (Mg) is known to occur through dislocation accumulation, grain refinement, deformation twinning, and texture control or dislocation pinning by solute atoms or nano-sized precipitates. These modes generate yield strengths comparable to other engineering alloys such as certain grades of aluminum but below that of high-strength aluminum and titanium alloys and steels. Here, we report a spinodal strengthened ultralightweight Mg alloy with specific yield strengths surpassing almost every other engineering alloy. We provide compelling morphological, chemical, structural, and thermodynamic evidence for the spinodal decomposition and show that the lattice mismatch at the diffuse transition region between the spinodal zones and matrix is the dominating factor for enhancing yield strength in this class of alloy.

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Body-centred cubic magnesium-lithium-aluminium-base alloys are the lightest of all the structural alloys, with recently developed alloy compositions showing a unique multi-dimensional property profile. By hitherto unrecognised mechanisms, such alloys also exhibit exceptional immediate strengthening after solution treatment and water quenching, but strength eventually decreases during prolonged low temperature ageing. We show that such phenomena are due to the precipitation of semi-coherent D0 3 -Mg 3 Al nanoparticles during rapid cooling followed by gradual coarsening and subsequent loss of coherency. Physical explanation of these phenomena allowed the creation of an exceptionally low-density alloy that is also structurally stable by controlling the lattice mismatch and volume fraction of the Mg 3 Al nanoparticles. The outcome is one of highest specific-strength engineering alloys ever developed.