Rolling Plastic Deformation Of Zr-based Amorphous Alloy Mechanical Properties

In this paper, the microstructure evolution due to rolling, the microhardness and the shear band morphologies during indentation of the Zr₆₅Al_7.5Cu_12.5Ni₁₀Ag₅ and Zr₆₀Al₁₅Ni₂₅ bulk amorphous alloys are investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC), high resolution transmission electron microscopy (HRTEM), microhardness tester and scanning electronic microscopy(SEM). The influence of microstructure changes due to rolling at room temperature on the mechanical properties and the shear band morphologies duirng indentation of the Zr₆₅Al_7.5Cu_12.5Ni₁₀Ag₅ and Zr₆₀Al₁₅Ni₂₅ bulk amorphous alloys is investigated. Then the relation between the mechanical properties and shear band morphologies during indentation is discussed. Some findings are obtained as following.A large number of localized shear bands are found in the rolled Zr₆₅Al_7.5Cu_12.5Ni₁₀Ag₅ and Zr₆₀Al₁₅Ni₂₅ samples, showing occurrence of inhomogeneous plastic deformation. The thickness reduction reaches 95% due to rolling. The results of XRD patterns show that no significant crystallization occurrs during rolling.With the increase of thickness reduction, the results of DSC curves and the structure relaxation show the free volume accumulated in the amorphous alloys is increase. And the microhardness of the Zr₆₅Al_7.5Cu_12.5Ni₁₀Ag₅ and Zr₆₀Al₁₅Ni₂₅ alloys decreases significantly. After annealing below the glass transition tempeature, the mechanical properties of the amorphous alloys recover.The results of bonded interface indentation show that semi-circle shear bands distribute regularly and smoothly in the as-cast Zr₆₅Al_7.5Cu_12.5Ni₁₀Ag₅ and Zr₆₀Al₁₅Ni₂₅ specimens and a small amount of ray shear bands exit. With the increase of thickness reduction, the shear bands morphology becomes more and more irregular. When the thickness reduction reached 50%, shear bands morphology completely becomes irregular. After annealing below the glass transition temperature, the shear bands morphology almost recovers.The results inidicate there exits a correlation between the shear band morphology and the mechanical property of an amorphous alloy. More regular the shear band morphology is, the higher mechanical property of an amorphous alloy. On the other hand, more irregular the shear band morphology is, the lower mechanical property of an amorphous alloy.