Study On Effect Of Microaddition On Properties And Non-Isothermal Crystallization Behavior In Cu-Zr-Al Amorphous Alloys

In this paper, Cu50Zr42Al8, Cu46Zr47-xAl7Yx(x=2,5), Cu43Zr42Al8Ag7, Cu43Zr42Al8Ag5Y2, Cu43Zr42Al8Ag5Gd2 and Cu43Zr42Al8Ag5Ni2 amorphous alloys were prepared with copper mould suction casting and single roller method. The glass-forming ability and non-isothermal crystallization kinetics were investigated by XRD and DSC. And the corrosion resistant properties comparative study of Cu-based amorphous alloys was carried out with electrochemical method. The author also analyzed how the addition of microcrystalline alloy has an influence on glass-formation ability, thermal stability and corrosion resistant capability of Cu-Zr-Al amorphous alloys.The structural characterization of Cu50Zr42Al8, Cu46Zr47-xAl7Yx(x=2,5), Cu43Zr42Al8Ag7 and Cu43Zr42Al8Ag5Y2 amorphous alloys was analyzed by XRD and the glass-forming ability of them was studied by means of DSC, whose results show that the glass-forming ability of Cu-Zr-Al amorphous alloy system is increased by adding Y and Ag separately or adding Y and Ag together to it, but the effect of Ag is more obvious. Compared to Cu50Zr42Al8, the Trg andγof Cu43Zr42Al8Ag7 and Cu43Zr42Al8Ag5Y2 both have been raised obviously, separately up to 0.619,0.416 and 0.609,0.411.The crystallization kinetics of Cu50Zr43Al8,Cu46Zr47-xAl7Yx(x=2,5), Cu43Zr42Al8Ag7 and Cu43Zr42Al8Ag5Y2 amorphous alloys were investigated by means of DSC under non-isothermal conditions. A lot of mathematical calculation shows that the above crystallization process of five kinds of amorphous alloys can be regarded as dynamics process depending on heating rate. For the same amorphous alloy, the activation energy is closely related with the formula. When describing the activation energy of different amorphous alloys, the same calculated method of the activation energy must be used in order to be compared reasonably. Cu43Zr42Al8Ag5Y2 has the highest effective activation energy in the beginning, which is 775.24 kJ/mol, meanwhile, it has the highest thermal stability. By calculating the activation phase crystallization energy of the sample, it shows that Cu43Zr42Al8Ag5Y2 also has the highest activation energy, and the thermal stability of Cu-Zr-Al amorphous alloy system is increased obviously by adding Ag and Y together. Comparingapparent activation energy and activation phase crystallization energyof Cu50Zr42Al8 to Cu46Zr45Al7Y2, we can know that the thermal stability of Cu-Zr-Al amorphous alloy system is decreased by adding Y, and the activation phase's crystallization energy of Cu46Zr45Al7Y2 is smaller than Cu46Zr42Al7Y5 obviously when the percentage of crystallization is less than 30%, because the trace crystallization is the particle of forming crystal, and the difference of activation phase's crystallization energy between Cu46Zr45Al7Y2 and Cu46Zr42Al7Y5 is not too much when the percentage of crystallization is more than 30%.Potentiodynamic curves of Cu43Zr42Al8Ag5Gd2 and Cu43Zr42Al8Ag5Ni2 in 0.lmol/L NaHSO3 solution and in 0.lmol/L NaCl solution was measured by means of electrochemical method, which shows that the corrosion resistant properties of amorphous alloys is much better than the correspondent crystallien alloy. The corrosion resistant properties of amorphous alloys are related with its structure and environment, but the components of alloys are more effective. Cu43Zr42Al8Ag5Gd2 shows active-passive polarization process in 0.lmol/L NaHSO3 solution, whose corrosion resistant properties is better than Cu43Zr42Al8Ag5Ni2.