Papers by Author: Wei Sun

Abstract: The microstructures and electrochemical corrosion behaviors of die-cast Mg-4Al-0.4Mn-xPr (x=0, 1, 4 wt.%) alloys have been investigated. Electrochemical behaviors of all alloys are described by open circuit potential test, potentiodynamic polarization test and electrochemical impedance spectroscope in 3.5 wt.% NaCl solution. The results show that the α-Mg grain is refined and the continuous net β phase appears gradually with increasing the content of Pr in the Mg-4Al-0.4Mn alloys. Moreover, the β phase plays a role of galvanic cathode in AM40 alloy and corrosion barrier in Pr-containing alloys, respectively. Electrochemical measurements show that Pr can improve corrosion resistance of Mg-4Al-0.4Mn alloy in the 3.5 wt.% NaCl solution, and corrosion rate decreases with increasing Pr content.

Abstract: Several Mg-4Al-4La/Ce alloys were developed and their microstructure and mechanical properties were evaluated. The phase compositions of Mg-4Al-4La alloy consist of α-Mg and Al11La3 phases. While two binary Al-RE phases, Al11RE3 and Al2RE (RE=Ce/La), are formed in Mg-4Al-4Ce/La alloy, and Al11Ce3 and Al2Ce are formed in Mg-4Al-4Ce alloy. The optimal tensile properties are obtained in Mg-4Al-4Ce/La alloy, in which the UTS, YS and δ are 250, 149.2 MPa and 12.24% at room temperature, and 157.8, 116 MPa and 27% at 150oC, and 99.1, 118.2 MPa and 23.2% at 250oC, respectively. The mechanics properties of Mg-4Al-4Ce/La alloy are nearly same with commercial AE44. The compression creep is lower than that AJ62 alloy.

Abstract: The relationship between structure, ionic radius and electronegativity and solubility of the various rare-earth elements in Mg was studied. It is found that light RE(La-Sm, Eu, Yb) have more complicated phase relation with Mg but the heavy RE(Gd-Lu, Sc) have the similar crystal structure with magnesium. Also it is found that the less electronegativity difference between Mg and RE is, the more solubility limit of RE in Mg is. The fact of the RE solubility decreased in magnesium with lowering temperature suggests that there is a possibility of Mg supersaturated solid solution formation and it will decomposition during aging. According to the rule, an megnesium alloy with higher strength feature was developed. Their mechanical properties are UTS 347MPa, YTS 290MPa and elongation 12.5% at room temperature.