Papers by Keyword: Number Density

Abstract: Two 6xxx alloys with different Mn-content have been homogenised in a furnace at 575 ^oC for 2 hours and 15 minutes. Three different heating rates to the homogenisation holding temperature were chosen, as this was expected to affect the precipitation behaviour of the dispersoids. The study focused on developing a reliable procedure for the characterization of the density and spatial distribution of dispersoids in aluminium alloys; both in terms of sample preparation, microscopic techniques and quantitative analyses of results. Scanning electron microscopy (SEM) has been used to evaluate the dispersoid characteristics for the different alloys and heating rates. The results indicate an increase in dispersoid number density and a more uniform distribution of dispersoids for the lowest heating rate, as compared to the more rapid heating rates, for the alloy with 0.05 wt% Mn. For the alloy with 0.15 wt% Mn the number density increased with the heating rate. This is suggested to be due to particle coarsening as an effect of the low heating rate where the samples spend longer time in the furnace.

Abstract: The mathematical model of soot dynamical evolution process is built based on the discrete particles population balance theory, including particle nucleation, collision coagulation, oxidation and surface growth processes; a corresponding numerical model is established using Lagrange interpolation method of moments. Based on the perfectly-stirred reactor combustion model, coupled the numerical model with detailed chemical kinetic model. The computing platform of soot particle growth evolution is established. Meanwhile, three nucleation models are built for the soot nucleation in this paper. Two chemical reaction mechanisms are used to study different fuels combustion process. The related information of soot particle growth evolution is obtained, the effect of different nucleation model on other dynamical events such as coagulation, oxidation and surface growth processes is discussed.

Abstract: The paper is mainly about reviewing on static phases of materials as numeric analyzing with its comparison to dynamical phases. All of analyzes are with based on dynamical and static equilibrium and its mode revision. Also, states changing in materials and their physical – chemical transfer changes have been covered by defined properties in this paper. We use some numeric solutions such as Boltzmann method in analyzing states in this paper.

Abstract: A new model of strain induced precipitation in niobium microalloyed austenite is proposed. This is based on the experimental observation of formation of microbands during hot deformation of iron – 30% nickel, which remains austenitic to room temperature. Precipitates are preferentially nucleated on nodes in the dislocation network in the microbands. This geometry enables features of earlier models to be simply explained, and facilitates extension of the model to multipass deformation. It is shown that the model captures all the essential features of previous experimental observations on microalloyed C – Mn steels. Currently, sensitivity analysis of the model and systematic experimental work are being undertaken to quantitatively validate the model.