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Microstructure evolutions of rapidly-solidified (RS) ribbon and conventionally cast bulk Mg-1 at%Zn-2 at%Y alloys have been studied by transmission electron microscopy (TEM), particularly focusing on formation process and phase stability of the long-period structures. It is found that there are significant differences in microstructural evolutions between the RS ribbon and the cast-bulk alloys, in terms of thermal stability of the long-period phases at temperatures higher than 673 K. For both the as-quench ribbon and the as-cast bulk specimens, 18R-type long-period phase is dominantly observed at grain boundaries. After annealing at temperatures higher than 673 K, the long-period phases at grain boundaries in the RS ribbon almost disappear to form Mg 24 Y 5 and Mg 3 Zn 3 Y 2 compounds within the grain interiors, while the long-period phases remained stable in the cast-bulk alloy even at temperatures higher than 673 K.

A reduction treatment using carbon powder for reducing TiO 2 to fabricate non-stoichiometric titanium dioxide, TiO 2Àx , was proposed and performed. The carrier density and non-stoichiometric number were calculated by using thermogravimetry (TG) while heating and re-oxidizing TiO 2Àx in air. The thermoelectric properties of TiO 2Àx were measured and evaluated in air. The results show that TiO 2Àx can be simply and safely obtained by reducing insulating TiO 2 through the proposed reduction treatment. The carrier density increases and non-stoichiometric number decrease with the temperature of the reduction treatment and have a good correspondence with the decrease in the electrical resistivity of TiO 2Àx . Significantly improved thermoelectric properties were observed as a consequence of the decreasing electrical resistivity of TiO 2Àx .