Isothermal kinetic diagram, phase

When a metal reacts with a gas containing more than one oxidant, a number of different phases may form depending on both thermodynamic and kinetic considerations. Isothermal stability diagrams, usually constructed with the logarithmic values of the activities or partial pressures of the two non-metallic components as... 

It is important to note that the treatments relating to the kinetics of phase transformations in Section 10.3 are constrained to the condition of constant temperature. By way of contrast, the discussion of this section pertains to phase transformations that occm with changing temperatirre.This same distinction exists between Sections 10.5 (Isothermal Transformatiorr Diagrams) and 10.6 (Continuous-Cooling Transformation Diagrams). 

Herein, we expand on the discussion of our recently observed isothermal amorphous-amorphous-amorphous transition sequence. We achieved to compress LDA in an isothermal, dilatometric experiment at 125 K in a stepwise fashion via HDA to VHDA. However, we can not distinguish if this stepwise process is a kinetically controlled continuous process or if both steps are true phase transitions (of first or higher order). We want to emphasize that the main focus here is to investigate transitions between different amorphous states at elevated pressures rather than the annealing effects observed at 1 bar. The vast majority of computational studies shows qualitatively similar features in the metastable phase diagram of amorphous water (cf. e.g. Fig.l in ref. 39) at elevated pressures the thermodynamic equilibrium line between HDA and LDA can be reversibly crossed, whereas by heating at 1 bar the spinodal is irreversibly crossed. These two fundamentally different mechanisms need to be scrutinized separately. 

Fig. 11.4 Comparison in the theoretical phase diagrams of phase separation and polymer crystallization in polymer solutions, and the kinetic phase diagrams of crystal nucleation. The energy parameters are set as EpIEc =1.0 and BlEc = 0.076 for the labeled Cl curves, EpjE = 1.072 and BjEc = 0.03 for C2, and EpjEc = 1.275 and BjEc = —0.1 for C3. Three solution series share the same melting points (solid lines) at polymer concentration ( = 0.125, but different depths of critical points for phase separation. The dashed lines are binodals, and the dotted lines are spinodals. The data points are the onset temperatures for the uprising of crystallite numbers on isothermal crystallization. The straight lines are drawn to guide the eyes (Zha and Hu2007) (Reprinted with permission)...

Numerous investigations have been done regarding the liquidus surface, die isothermal sections and the vertical sections in the stable and metastable systems. The other investigations on die ternary system concern the solubility measurements of carbon in the "y and liquid phases which go always widi activity measme-ments, the determination of the phase diagram under high pressures and die kinetics studies of die austenite transformation in martensite or bainite because these phases are important in die forecast of mechanical properties of steel. The main experimental investigations on crystal structure, phase equilibria and thermodynamics are gathered in Table 1. 

Undersaturated clear solutions of CBZ and NCT were obtained at 45 °C, and then cooled quickly to 25 °C. An isothermal plateau was then applied until equilibrium was reached. Crystal nucleation and growth occurred only during this isothermal step. Figure 9.5 displays three kinetic pathways in the phase diagram from representative experiments started in three domains where two solid phases may develop. 

Rousset [30] used a model called FEM-TTT. The software, based on a model originally developed for metal solidification [45,46], is able to calculate the kinetics of the phase transformation for any thermal path, using experimental isothermal crystallization kinetics data represented by the time-temperature-transformation (TTT) diagrams and an additivity principle, in a Cartesian bidimensional... 

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