The effects of minor Ce on the microstructure, mechanical properties and corrosion behaviour of Mg-3Sn-1Ca alloy are investigated systematically. The minor Ce can refine the eutectic structure between α-Mg and CaMgSn and make the microstructure more uniform. The maximum ultimate tensile strength and elongation of the alloy with the Ce content of 0.3 wt-% were 152.5 MPa and 4.1%, respectively. Meanwhile, the corrosion resistance of the Ce-containing alloys is improved by Tafel curves and electrochemical impedance spectra, especially when the Ce is up to 0.3 wt-%. The minor Ce can promote the formation of the surface film and makes the corrosion product film to become more compact, which effectively prevents further the occurrence of corrosion of the Mg matrix.

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Fe-20Mn-0.7C twinning-induced plasticity (TWIP) steel with the grain sizes in the range 1.7-10.2 μm was produced by cold rolling and annealing. The effects of grain sizes on the mechanical properties of the TWIP steel were studied by tensile test at room temperature (RT) and-180°C. The yield strength increased with decreasing grain size at RT and-180°C, and the corresponding Hall-Petch relationships were established at both temperatures and are as follows (i) σ 0.2 = 205 + 453 d-1/2 (at RT) and (ii) σ 0.2 = 317 + 755 d-1/2 (at-180°C). When the temperature decreased from RT to-180°C, the stacking fault energy decreased from 24to 17.9 mJ/m 2 , approximately 25%, and the deformation mode is transformed from deformation twins to martensite transformation.