Study On Related Phase Equilibria Of The Al-Zn-Fe-Ce Quaternary System At 600 ℃

Hot-dip galvanizing is one of the most effective methods for improving the corrosion resistance of steel. However, with the rapid development of modern industry and the deterioration of environment,and the pure zinc coating is far from meet the more stringent requirements on the performance of the coating that put forward by human beings. For this reason, in the 1960 s, hot-dip Zinc-Aluminum became the focus in hot-dip industry. Among them, the 55%Al-Zn coating is developed rapidly because of its excellent performance in resistance to corrosion. But some problems still exist in the actual production process, for example, the impurity effect the apparent quality and corrosion resistance of coating. Adding rare earth metal in the molten pool can greatly reduced the viscosity of liquid metal and purify the impurities. The addition of rare earth(Ce、La et al) in the 55%Al-Zn plating solution can improve the plating solution on steel substrate wettability and greatly enhance the quality of the coating. In this work, the Al-Zn-Fe-Ce quaternary system and related ternary system are investigated to lay the theoretical fundament of analyzing the effect of Ce in hot-dip galvalume.In this work equilibrated alloys were utilized with the help of scanning electron microscope equipped with dispersive X-ray spectroscope and X-ray power diffraction to determine the phase relations of the Al-Zn-Ce and Al-Fe-Ce ternary systems at 600°C and the Al-Zn-Fe-Ce quaternary system with Al being fixed at 75 at.% at 600°C. Fifteen three-phase regions and two ternary phases τ1 and τ2 have been determined experimentally in the Al-Zn-Ce isothermal section at 600 ℃. γCe+Al Ce3+Al Ce 、 Ce Zn+Al Ce+τ1、 Ce Zn+Ce Zn2+τ1、 Ce Zn2+τ1+τ2、Ce Zn2+Ce Zn3+τ2、Ce Zn3+Ce3Zn11+τ2、Ce3Zn11+Ce13Zn58+τ2、Ce13Zn58+Ce Zn5+τ2、Ce Zn5+Ce3Zn22+τ2、Ce3Zn22+Ce2Zn17+τ2、Ce2Zn17+Ce Zn11+τ2、Al Ce+Al2Ce+τ2、ɑAl3Ce+ɑAl11Ce3+τ2、ɑAl11Ce3+ɑ-Al+τ2、ɑ-Al+Liq.+τ2. In the Al-Fe-Ce isothermal section at 600 ℃, fifteen three-phase regions have been determined experimentally. ɑ-Al+ɑAl11Ce3+Ψ 、 ɑAl11Ce3+ɑAl3Ce+Ψ 、 ɑAl3Ce+Ψ2+Ψ 、 ɑAl3Ce+Al2Ce+Ψ2、Al2Ce+Ψ2+Ψ3、Al2Ce+Ψ3+Ψ4、Al2Ce+Ψ4+Ψ5、Al2Ce+Al Ce+Ψ5、Al Ce+Al3Ce+Ψ6、Al Ce3+γCe+Ψ6、Ψ+ɑ-Al+Fe Al3、Ψ+Ψ2+Fe Al3、Fe Al3+Ψ2+Ψ3、Fe2Al5+Ψ3+Fe Al3、Fe2Al5+Fe Al2+Ψ3. There are six ternary phases Ψ-Ce Fe2Al10 、 Ψ2-Ce Fe2Al7 、Ψ3-Ce Fe4Al8、Ψ4(to be determined)、Ψ5-Ce5Fe4Al6、Ψ6(to be determined) have been determined in the isothermal section.The result of research indicate that, in the Al-Zn-Fe-Ce quaternary system with Al being fixed at 75 at.%, there exist four four-phase fileds: τ2+Fe Al3+ɑ-Al+Liq.、τ2+Fe Al3+ɑ-Al+Ψ、ɑ-Al+Ψ+τ2+ɑAl11Ce3、Ψ+τ2+ɑAl11Ce3+ɑAl3Ce. No new quaternary phase was found in this section.