Rheological measurements of bulk metallic glass forming alloys above the liquidus temperature

Graduation date: 2005A high temperature high vacuum rheometer has been designed, fabricated,\ud and tested for the study of the steady shear viscosity for multicomponent bulk\ud metallic glass forming alloys. This rheometer has an operating range up to\ud 1525 K, rotational frequencies of 9.4*10⁻³-3.7*10¹ radians/s, and a\ud calibrated viscosity range of 9.6*10⁻³ and 1.2*10² Pa*s while maintaining\ud absolute pressures pressure < 1*10⁻⁶ mbar.\ud Zr[subscript 41.2]Ti[subscript 13.8]Cu[subscript 10.0]Ni[subscript 12.5]Be[subscript 22.5] (Vitreloy 1) is reported. The unexpected findings\ud of non-Newtonian behavior above the liquidus temperature were observed.\ud Observations of shear thinning, thixotropic, and viscoelastic behaviors have\ud been made. Our results show that Vitreloy 1 can be modeled as a power law\ud fluid, with a power law exponent of approximately -0.5 for high shear rates.\ud We attribute the non-Newtonian behavior to structural ordering within the\ud melt. The technological and scientific implications for non-Newtonian behavior are discussed