Bulk metallic glasses (BMGs) offer a great deal of potential through their near-theoretical strength, potentially high toughness and unique forming and molding traits. However, there are still a number of outstanding issues that bar their widespread use. This thesis describes the investigation of three research questions each designed to further...
By the investigation of the bulk metallic glass-forming liquids that have very low critical cooling rates, the thermodynamics of metallic glasses can be clarified. For studying thermodynamic properties, such as the specific heat capacity, calorimetry (DSC) is utilized and one of the most used instruments is the differential scanning calorimeter....
The heating rate dependence of the glass transition temperature of the
Ni₆₅Nb₃₅, Ni₆₀Nb₃₅Sn₅, Ni₅₉.₃₅Nb₃₄.₄₅Sn62, Ni₆₀(Nb₄₀Ta₆₀)₃₄Sn₆, and
Ni₅₇Fe₃Nb₃₅Sn₅ metallic glass forming alloys was investigated with a
differential scanning calorimeter (DSC). The inverse heating rate for each
DSC experiment was plotted versus inverse temperature and a Vogel-Fulcher-
Tamman (VFT) type relation was...
Among recently found multi-component Zr-based bulk metallic glasses (BMG), Zr₅₈.₅Cu₁₅.₆Ni₁₂.₈Al₁₀.₃Nb₂.₈ is characterized by its lower critical cooling rate requirement and absence of beryllium as one of the constituent element which makes its handling more convenient. Its large supercooled liquid regions made possible the study of thermodynamics and kinetics of this...
A high temperature high vacuum rheometer has been designed, fabricated,
and tested for the study of the steady shear viscosity for multicomponent bulk
metallic glass forming alloys. This rheometer has an operating range up to
1525 K, rotational frequencies of 9.4*10⁻³-3.7*10¹ radians/s, and a
calibrated viscosity range of 9.6*10⁻³ and...
A Bulk Metallic Glass (BMG) is an amorphous solid with thickness greater than 1mm. Material properties of BMG, like twice the strength of regular steels and excellent corrosion resistance, make them ideal materials for fabrication of MEMS and MECS devices which have attracted a lot of research activity recently. Diffusion...
Dental resin composites are widely used in modern dentistry due to their aesthetic appearance. However, resin based restorations have inferior mechanical properties (fracture is the second reason for restorations replacement) in comparison to alloy based composites and their antimicrobial properties still remain poor, leading to secondary tooth decay development on...
Amorphous metal thin films lack the grain boundaries and dislocations present in
crystalline metal films. As a result, amorphous metal films can be more mechanically robust, atomically smooth, and more resistant to chemical attack than crystalline metals. However, amorphous metals are meta-stable and subject to crystallization upon heating, thus limiting...