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The corrosion behaviour of Mg-Mn and Mg-Mn-Zn magnesium alloy in a phosphate buffered simulated body fluid (SBF) has been investigated by electrochemical testing and weight loss experiment for bone implant application. Long passivation stage and noble breakdown potential in the polarization curves indicated that a passive layer could be rapidly formed on the surface of magnesium alloy in the phosphate buffered SBF, which in turn can protect magnesium from fast corrosion. Surfaces of the immersed magnesium alloy were characterized by SEM, EDS, SAXS and XPS. Results have shown that Mg-Mn and Mg-Mn-Zn alloy were covered completely by an amorphous Mg-containing phosphate reaction layer after 24 h immersion. The corrosion behaviour of magnesium alloys can be described by the dissolving of magnesium through the reaction between magnesium and solution and the precipitating of Mg-containing phosphate on the magnesium surface. Weight loss rate and weight gain rate results have indicated that magnesium alloys were corroded seriously at the first 48 h while Mg-containing phosphate precipitated fast on the surface of magnesium alloy. After 48-96 h immersion, the corrosion reaction and the precipitation reaction reach a stable stage, displaying that the phosphate layer on magnesium surface, especially Zn-containing phosphate layer could provide effective protection for magnesium alloy.

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Titanate nanotube thin (TNT) films were synthesised by alkaline hydrothermal method using titanium (Ti) plates as precursors. Copper-cobalt (Cu-Co)-codoped titanate/Ti dioxide (TiO 2) nanocomposite thin films were prepared by doping Cu and Co to TNT films through ion exchange method and annealed at 500°C for 120 min. The as-prepared nanocomposite films were characterised by scanning electron microscopy, transmission electron microscopy, X-ray diffractometer, and ultraviolet-visible absorption spectra. The results show that anatase TiO 2 particles were grown on the surface of titanate nanomaterial films. The composite materials mainly consisted of anatase TiO 2 particles and titanate nanotubes/nanosheets. Cu-Co-codoped titanate/TiO 2 nanocomposite thin films exhibited superior visible height adsorption property due to the reduced energy bandgap of composites introduced by additional Cu and Co 3d orbitals.

Aluminum alloys have the advantages of low density, high specific strength, good ductility and easy recycling. As structural materials, they are widely applied in the fields of aerospace, automobiles, electronics and rail transportation. However, the coarse grain of as-cast aluminum alloy reduced the mechanical properties and significantly reduced the subsequent rolling properties. To solve this problem, the most common method in industry is to introduce Al-Ti-B refiner to obtain fine equiaxed grains, with the aim to improve the comprehensive mechanical properties and calendering ability of aluminum alloy [1][2] .The synthetic method of Al-Ti-B grain refiner was mainly a fluoride salt method. However, the potassium fluoroaluminate, as by-product, is adulterated into the Al-