Compositional dependence of thermal and elastic properties of Cu-Ti-Zr-Ni bulk metallic glasses

Starting from the quaternary Cu(47)Ti(34)Zr(11)Ni(8) alloy, the compositional dependence of thermal and elastic properties of Cu-Ti-Zr-Ni alloys was systematically investigated. Quaternary Cu-Ti-Zr-Ni alloys can be cast directly from the melt into copper molds to form fully amorphous strips or rods with the thickness of 3-6 mm. The evidence of the amorphous nature of the cast rods was provided by X-ray spectra. The measured glass transition temperature (T(g)) and crystallization temperature (T(x)) were obtained for the alloys using differential scanning calorimetry (DSC) at the heating rate of 20 K/s. In the results, the differences between the glass temperature and the crystallization temperature (Delta T(x)=T(x)-T(g)) are measured with values ranging up to 33-55 K. The reduced glass transition temperature (T(rg)), which is the ratio of the glass temperature to the liquidus temperature (T(1)), is often used as an indication of the glass-forming ability of metallic alloys. For the present Cu-Ti-Zr-Ni alloys, this ratio is typically in the range of 0.5838-0.5959, characteristic of metallic alloys with good glass-forming ability. The elastic constants for several selected alloys were measured using ultrasonic methods. The values of the elastic shear modulus, bulk modulus, and Poisson's ratio were also given.