Thermal characterization of Cu60ZrxTi40−x metallic glasses (x=15, 20, 22, 25, 30)

The crystallization behavior, the thermal stability and the microhardness of Cu60ZrxTi40−x amorphous alloys (x=15, 20, 22, 25, 30) prepared by melt-spinning have been studied by means of differential scanning calorimetry (DSC), differential thermal analysis (DTA), X-ray diffraction (XRD) and microhardness tests. DSC analysis have confirmed the existence of glass transition, followed by a supercooled liquid region in all the compositions. However, depending on the Zr content, different crystallization behavior has been observed. The apparent activation energies of the crystallization processes have been determined and the obtained values indicate high thermal stability for all the alloys. XRD-patterns of the as-quenched samples showed a broad symmetric halo typical of a fully amorphous structure. Independently of the composition, after the first crystallization stage the XRD patterns present a structure similar to that of an amorphous one. But the final developed microstructure depends on the composition of the alloys. The addition of Zr has not shown significant differences in microhardness of the amorphous alloys, although they have exhibited good mechanical properties.