NANOCRYSTALLINE Ni Al ALLOY OBTAINED BY MECHANICAL
... Nanocrystalline Ni3Al alloy obtained by mechanical alloying and subsequent heating On the basis of the XRD results we can conclude that for both milled compositions – Al3Ni + Ni and Ni96Al4 + Al powder mixtures – in the first step of milling small zones of supersaturated fcc Ni(Al) solid solution f ...
... Nanocrystalline Ni3Al alloy obtained by mechanical alloying and subsequent heating On the basis of the XRD results we can conclude that for both milled compositions – Al3Ni + Ni and Ni96Al4 + Al powder mixtures – in the first step of milling small zones of supersaturated fcc Ni(Al) solid solution f ...
ACTIVATION ENERGY VARIATION DURING IGNITION OF
... The ignition of gaseous flammable mixtures on hot solid surfaces is a frequent phenomenon having numerous implications and applications in a variety of combustion problems [1y3]. Special aspects connected with this subject arise from the catalytic effect of solid surfaces [4y5]. Particularly, the ca ...
... The ignition of gaseous flammable mixtures on hot solid surfaces is a frequent phenomenon having numerous implications and applications in a variety of combustion problems [1y3]. Special aspects connected with this subject arise from the catalytic effect of solid surfaces [4y5]. Particularly, the ca ...
chemistry
... Directions (1–30): For each statement or question, write in your answer booklet the number of the word or expression that, of those given, best completes the statement or answers the question. Some questions may require the use of the Reference Tables for Physical Setting/Chemistry. 8 At STP, both d ...
... Directions (1–30): For each statement or question, write in your answer booklet the number of the word or expression that, of those given, best completes the statement or answers the question. Some questions may require the use of the Reference Tables for Physical Setting/Chemistry. 8 At STP, both d ...
1985 Free Response Answers
... [delta]H > 0 since heat is required to change liquid water to vapor. [delta]S > 0 since randomness increases when a liquid changes to vapor. [delta]G < 0 since the evaporation takes place in this situation. [delta]T < 0 since the more rapidly moving molecules leave liquid first. The liquid remaing i ...
... [delta]H > 0 since heat is required to change liquid water to vapor. [delta]S > 0 since randomness increases when a liquid changes to vapor. [delta]G < 0 since the evaporation takes place in this situation. [delta]T < 0 since the more rapidly moving molecules leave liquid first. The liquid remaing i ...
Molarity = moles of solute liters of solution M1V1 = M2V2
... Introduction: A solution is a mixture of two or more substances in a single phase. At least two substances must be mixed in order to have a solution. The substance in the smallest amount and the one that dissolves or disperses is called the SOLUTE. The substance in the larger amount is called the SO ...
... Introduction: A solution is a mixture of two or more substances in a single phase. At least two substances must be mixed in order to have a solution. The substance in the smallest amount and the one that dissolves or disperses is called the SOLUTE. The substance in the larger amount is called the SO ...
Theoretical Studies on the Effect of Confinement on Quantum Dots
... only become important in very small nanocrystals or for nanocrystals with an exceptionally low work function. This infinite potential barrier approximation also implies that Eg(R) is insensitive to an externally applied potential and to the surroundings of the nanocrystal. The effect of the surround ...
... only become important in very small nanocrystals or for nanocrystals with an exceptionally low work function. This infinite potential barrier approximation also implies that Eg(R) is insensitive to an externally applied potential and to the surroundings of the nanocrystal. The effect of the surround ...
Chapter 7: Solutions
... Solutions: Solubility The formation of liquid solutions, such as Kool Aid or dissolved NaCl, requires that solute particles be able to interact with the solvent molecules through ...
... Solutions: Solubility The formation of liquid solutions, such as Kool Aid or dissolved NaCl, requires that solute particles be able to interact with the solvent molecules through ...
Spinodal decomposition
Spinodal decomposition is a mechanism for the rapid unmixing of a mixture of liquids or solids from one thermodynamic phase, to form two coexisting phases. As an example, consider a hot mixture of water and an oil. At high temperatures the oil and the water may mix to form a single thermodynamic phase in which water molecules are surrounded by oil molecules and vice versa. The mixture is then suddenly cooled to a temperature at which thermodynamic equilibrium favours an oil-rich phase coexisting with a water-rich phase. Spinodal decomposition then occurs when the mixture is such that there is essentially no barrier to nucleation of the new oil-rich and water-rich phases. In other words, the oil and water molecules immediately start to cluster together into microscopic water-rich and oil-rich clusters throughout the liquid. These clusters then rapidly grow and coalesce until there is a single macroscopic oil-rich cluster, the oil-rich phase, and a single water-rich cluster, the water-rich phase.Spinodal decomposition can be contrasted with nucleation and growth. There the initial formation of the microscopic clusters involves a large free energy barrier, and so can be very slow, and may occur as little as once in the initial phase, not throughout the phase, as happens in spinodal decomposition.Spinodal decomposition is of interest for two primary reasons. In the first place, it is one of the few phase transformations in solids for which there is any plausible quantitative theory. The reason for this is the inherent simplicity of the reaction. Since there is no thermodynamic barrier to the reaction inside of the spinodal region, the decomposition is determined solely by diffusion. Thus, it can be treated purely as a diffusional problem, and many of the characteristics of the decomposition can be described by an approximate analytical solution to the general diffusion equation.In contrast, theories of nucleation and growth have to invoke the thermodynamics of fluctuations. And the diffusional problem involved in the growth of the nucleus is far more difficult to solve, because it is unrealistic to linearize the diffusion equation.From a more practical standpoint, spinodal decomposition provides a means of producing a very finely dispersed microstructure that can significantly enhance the physical properties of the material.