Formation Ability And Characterization Of Zr-Based Amorphous Alloys

In the paper, a set of single roller device has been manufactured according to rapid solidification principle, which is applied to produce the amorphous alloys and the rapid solidification characteristics of Zr-based alloy have been studied. By coupling of the energy equation and the Navier-Stokes equation, the cooling rate of the alloy is calculated theoretically. Meanwhile, using Takeuchi modified model, the critical cooling rate of forming amorphous alloy is also estimated. The structural characteristics of Zr-based amorphous alloy have been studied by using XRD, TEM and DSC analysis techniques, and the electrical resistivity, tensile strength and elongation of Zr-based amorphous alloys are quantificationally characterized. The relations of cooling rate and microstructure morphology with alloy properties are also investigated.During rapid solidification, the temperature of puddle changes more significant along the vertical direction than that in the horizontal direction. The alloy melt changes its flow rate and velocity direction rapidly at about 250μm height. The horizontal flow velocity increases rapidly, but the vertical flow velocity decreases sharply, both of them tend to be stable when x>0.6mm. The cooling rate of the alloy increases with the increase of the wheel velocity. The alloy foils prepared with the compositions of Zr_xAl_yNi_zCu_(100-x-y-z)(x=45,55,65; y=8,10,12; z=3, 5, 7) are all amorphous. The glass forming ability of Zr₅₅Al₁₂Ni₃Cu₃₀ alloy is the best, whoes critical cooling rate is merely 4.7K/s, much lower than others, whereas, the critical cooling rate of Zr₄₅Al₁₂Ni₇Cu₃₆ is much higher to 610K/s.The results of the orthogonal test indicate that: the Zr₄₅Al₁₂Ni₇Cu₃₆ amorphous alloy foils obtained has the best properties when the wheel velocity is controlled at 40m/s.The cooling rate has significant influence on the properties of the amorphous alloy. With the increase of the cooling rate, the tensile strength and electrical resistivity of Zr₄₅Al_xNi_x-5Cu_60-2x(x=8, 10, 12) amorphous alloy increase, but the elongation decreases.