Effects Of Rare Earth Element Y On Glass-Forming Ability And Corrosion Behavior Of Zr-based Amorphous Alloy

As a typical Zr-based amorphous alloy system,Zr-Cu-Ni-Al amorphous alloy system is a new type of bulk amorphous alloy in recent years,which has high glass-forming ability,excellent mechanical properties and corrosion resistance.It was found that the addition of trace rare earth elements had a great influence on the properties of amorphous alloys.In this paper,Zr53.8Cu29.iNi7.3Al9.8 amorphous alloy was chosen as the matrix,and the effects of rare earth element Y on glass-forming ability and corrosion behavior of Zr-based amorphous alloys were investigated by replacing Zr with a small amount of Y.It is of great academic significance and guidance value to deeply understand the performance feature of Zr-based bulk amorphous alloy and apply these new materials scientifically and reasonably.First of all,the preparation of amorphous alloy with two deep eutectic alloy smelting and die casting of water cooled copper mold.The compositions of binary eutectic master alloys were Zr44Cu56,Zr64Ni36,Zr51Al49 and Al25Y75,which were determined by binary alloy phase diagram.And then,Zr53.8Cu29.1Ni7.3Al9.8 and Zr52.8Cu29.1Ni7.3Al9.8Y1 amorphous alloys were prepared at 1523K,1623K and 1723K diecasting temperatures.The glass-forming ability of these two amorphous alloys was studied by X-ray diffraction(XRD),transmission electron microscopy(TEM)and differential scanning calorimetry(DSC).The results of XRD showed that the XRD patterns of Zr52.8Cu29.1Ni7.3Al9.8Y1 are more uniform than those of Zr53.8Cu29.iNi7.3Al9.8 at the same temperature,and the number of crystal peaks in Zr52.8Cu29.1Ni7.3Al9.8Y1 is smaller.The results of TEM showed that the diffraction pattern of Zr52.8Cu29.1Ni7.3Al9.8Y1 had fewer diffraction spots and a better amorphous uniformity.The results of DSC showed that the width(ΔTx)of the supercooled liquid region of Zr52.8Cu29.1Ni7.3Al9.8Y1 was about 12K higher than that of Zr53.8Cu29.1Ni7.3Al9.8,showing better glass-forming ability and thermal stability.It has been indicated that the addition of a small amount of rare earth element Y improve the glass-forming ability and thermal stability of Zr52.8Cu29.1Ni7.3Al9.8Y1 amorphous alloy to a certain extent.The corrosion behavior of the two kinds of amorphous alloys was studied by electrochemical method.And the corrosion morphology of the two amorphous alloys was observed and analyzed by scanning electron microscopy(SEM)and its own energy dispersive spectrometer(EDS).In 3.5%NaCl solution,severe pitting corrosion occurred on the surface of both amorphous alloys due to the autocatalytic effect of Cl-,within which Zr52.8Cu29.1Ni7.3Al9.8Y1 had a smaller self-corrosion current density and a larger pitting potential.In 0.5mol/L H2SO4 solution and 4mol/L NaOH solution,both amorphous alloys were all passivated,without very severe corrosion traces,and Zr52.8Cu29.1Ni7.3Al9.8Y1 had a more positive self-corrosion potential and smaller self-corrosion current density.The results show that the addition of rare earth element Y improve the formation of Zr-rich passivation film and corrosion resistance of Zr52.8Cu29.1Ni7.3Al9.8Y1 amorphous alloy to a certain extent.The average corrosion rate was calculated by the soaking method,and the corrosion morphology of two amorphous alloys was observed by SEM.In NaCl and H2SO4 solution,both amorphous alloys showed excellent corrosion resistance,and the average corrosion rate was gradually increasing with the concentration increasing.The average corrosion rate of Zr52.8Cu29.1Ni7.3Al9.8Y1 was slightly smaller than that of Zr53.8Cu29.1Ni2.3Al9.8,and the number and density of surface corrosion trace of Zr52.8Cu29.1Ni7.3Al9.8Y1 were also slightly smaller.In NaOH solution,the average corrosion rate of two amorphous alloy was almost zero,and almost no visible corrosion marks existed on the surface of the specimen.In summary,the addition of a small amount of rare earth element Y improve the glass-forming ability and the corrosion resistance of the Zr-based amorphous alloy to a certain extent.It makes Zr52.8Cu29.1Ni7.3Al9.8Y1 amorphous alloy have greater glass-forming ability and better corrosion resistance.