This study utilizes differential scanning calorimetry (DSC) to characterize the thermodynamics, kinetics and crystallization b processes of a new Pt₅₇.₃Cu₁₄.₆Ni₅.₃P₂₂.₈ bulk metallic glass forming alloy. The heat capacity of the alloy is measured for the crystalline, glassy, and supercooled liquid phases. This data is used to obtain thermodynamic driving forces...
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...
The effect of ambient environment on the fatigue behavior of two Zr-Ti-Cu-Ni-Be bulk metallic glasses (BMGs) is examined in the present study. The first metallic glass, Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅, was tested to establish the presence of an environmental effect in the fatigue growth curve measured in ambient air. Fatigue growth curves produced...
Deformation of metallic glasses requires the existence of free volume to allow atomic movement under mechanical loading. Accordingly, the present research seeks to understand how free volume variations in alloys of identical compositions affect the fatigue and fracture behavior. By annealing below the glass transition temperature, the free volume of...
Bulk metallic glasses (BMGs) are relatively new amorphous materials that have received much attention in recent years. Rapid cooling methods from the liquid state provides the possibility to bypass crystallization during solidification. Due to the lack of crystal defects such as grain boundaries and dislocations, BMGs can have some special...
The viscosity of Zr[subscript 41.2]Ti[subscript 13.8]Cu[subscript 12.5]Ni[subscript 10.0]Be[subscript 22.5] (Vit1) has been measured above the liquidus temperature, T[subscript liq]=1026 K, using a high vacuum high temperature rapid annealing furnace equipped with a Couette Concentric Cylinder Rheometer. Steady state measurements have been taken over a temperature range of 1075-1300 K and...
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...
The development of amorphous metal alloys with high glass forming ability allows the fabrication of amorphous samples with thickness greater than 1mm, known as bulk metallic glasses(BMGs). Outstanding mechanical properties and ease in processing due to low melting points, low solidification shrinkage and higher supercooled liquid region make BMG a...