Time filter

Source Type

Dhurandhar H.,Narsee Monjee Institute of Management and Higher Studies | Lad K.N.,Condensed Matter Physics Laboratory | Pratap A.,Condensed Matter Physics Laboratory
Solid State Phenomena | Year: 2011

The crystallization kinetics of metallic glass Ti50Cu 20Ni30 has been studied using Differential Scanning Calorimetry (DSC). The DSC thermograms have been analysed using the model-free isoconversional methods and model dependent isokinetic methods. The activation energy(E) for the crystallization process has been determined utilizing; (i) various linear integral isoconversional methods, namely, Ozawa-Flynn-Wall, Kissinger-Akahira-Sunose, Li Tang method (ii) linear differential isoconversional method and (iii) different isokinetic methods. In the present work, we intend to the determination of true value of E. The above methods are found to give consistent results for E. © (2011) Trans Tech Publications, Switzerland.


Patel A.T.,Condensed Matter Physics Laboratory | Lad K.N.,Condensed Matter Physics Laboratory | Pratap A.,Condensed Matter Physics Laboratory
Solid State Phenomena | Year: 2011

Knowledge of glass forming ability (GFA) of amorphous metallic alloys is very important from both theoretical and practical point of view. Thermodynamically, the Gibbs free energy difference, ΔG between the undercooled liquid and the corresponding crystalline state is driving force for crystallization. As a consequence, it is a good indicator for glass forming ability of metallic glasses. A novel expression for ΔG has been used to estimate the GFA of recently developed Ca-based bulk metallic glasses viz. Ca53Mg23Cu24, Ca65Mg 15Cu20, Ca40Mg25Cu35, Ca50Mg22.5Cu27.5 and Ca55Mg 15Cu30. Different GFA criteria are also evaluated for systems taken up in the study and effect of addition of variation in composition of Ca-Mg-Cu system is also investigated. Present work suggests that among different GFA criteria, ΔG is the best criterion for the prediction of GFA for Ca-based bulk metallic glasses. © (2011) Trans Tech Publications, Switzerland.


Bhatt P.A.,Condensed Matter Physics Laboratory | Pratap A.,Condensed Matter Physics Laboratory | Jha P.K.,Bhavnagar University
Journal of Thermal Analysis and Calorimetry | Year: 2012

The size and shape effects on melting, glass transition, and Kauzmann temperatures of SnO2 nanoparticles using Lindemann's criterion have been studied. The melting temperature of SnO2 nanoparticles decreases as the size of the particle decreases. As the particle size increases, melting temperature increases and approaches to the melting temperature 1,903 K of bulk irrespective of the shape. The glass transition and Kauzmann temperatures are analyzed through the size effect on the melting temperature. The glass transition and Kauzmann temperatures decrease with the decrease in size of SnO2 nanoparticles. © Akademiai Kiado, Budapest, Hungary 2012.


Patel A.T.,Condensed Matter Physics Laboratory | Pratap A.,Condensed Matter Physics Laboratory
Journal of Thermal Analysis and Calorimetry | Year: 2012

In this study, the kinetics of glass transitions of Ti50Cu 20Ni30 and Fe67Co18B 14Si1 metallic glasses are studied using thermal analysis technique, i.e., differential scanning calorimetry, by means of continuous heating of the sample at various heating rates. In the present study, based on the heating rate dependence of glass transition temperature (Tg), the activation energy (E) of the glass transition region is determined by two most frequently used approaches, i.e., Moynihan's method and Kissinger's equation. The fragility index, m, is also calculated using Tg, which is a measure of glass-forming ability of the given system. The result shows that the fragility index, m, of the given systems is <16. This indicates that the given systems are strong liquids with excellent glass-forming ability. © Akademiai Kiado, Budapest, Hungary 2012.

Loading Condensed Matter Physics Laboratory collaborators
Loading Condensed Matter Physics Laboratory collaborators