Microstructural characterization of rapidly solidified Cu50Zr40Ni5Ti5 amorphous alloy

Abstract

The amorphous Cu50Zr40Ni5Ti5 alloy was produced by melt-spinning at wheel speeds of 35,38 and 41 m s(-1). The resulting melt-spun ribbons were characterised using X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDX), differential scanning calorimetry (DSC) and Vickers microhardness (HV) tester. The XRD and SEM results revealed that the rapidly solidified ribbons have a fully amorphous structure. After partial or fully crystallisation of Cu50Zr40Ni5Ti5 ribbons upon annealing, the microstructure had uneven and irregularly shaped features with the existence of Cu10Zr7, Cu8Zr3, CuZr and FCC-Cu phases while as quenched ribbons had featureless microstructure. The SEM-EDX analysis confirmed compositional homogeneity of the Cu50Zr40Ni5Ti5 alloy ribbon. According to DSC results, the amorphous ribbons exhibited distinct glass transition temperature (T-g) and wide supercooled liquid region (Delta T-x = T-x-T-g) before crystallization. Accordingly, T-g and Delta T-x are around 409-414 degrees C and 37-54 degrees C, respectively. The microhardness of the as-quenched ribbons was about 522 HV while it decreased with increasing annealing temperature and had a value of 463 HV for 725 degrees C. (C) 2014 Elsevier B.V. All rights reserved.