Precipitation kinetics of complex precipitate in multicomponent systems

A kinetic model based on the classical nucleation and growth theory has been proposed to predict the precipitation behavior of complex precipitate. The method for calculating absolute solution temperature, which is an important guidance for determining solution treatment temperature, is also proposed based on thermodynamic model. In the model, nucleation of the second phase is assumed to be controlled by the effective diffusion, which involves the bulk diffusion and dislocation pipe diffusion, and growth is controlled by the bulk diffusion of forming elements. The interfacial energy of complex precipitate is calculated by the linear interpolation method, and the effects of alloying elements on precipitation behavior are manifested using weighted means of their diffusivities and concentration. The predictions were compared with the experimental measurements, and a good agreement was obtained.

Complex Precipitation Mechanism of Ti-Nb-V Microalloyed Bainitic Base High Strength Steel

The addition of high Ti（>0.1%） in microalloyed bainitic high strength steel was designed, and the precipitation morphology of steels with different Ti, Nb, and V contents was studied by utilizing transmission electron microscopy（TEM）. Based on the classical nucleation-crystal growth theory and the Johnson-Mehl-Avrami equation, the precipitation thermodynamic and kinetic model of second phase particles in austenite was established in the form of（Nbx,Vy,Tiz）C, and the complex precipitation mechanism of second phase particles was emphatically studied. The experimental results show that the complex precipitation particles could be divided into two categories: the coarser particles with about 100 nm grain size and the independent complex precipitation particles in the form of（Nb,V,Ti）C with 35-50 nm grain size. The latter has a better precipitation strengthening effect, and the calculated PTT curve shows a typical "C" shape. When the deformed storage energy is 3 820 J?mol-1, the fastest precipitation temperature of calculated PTT curve is 925 °C, and the calculated result is essentially consistent with experimental values. The increase of Ti content increased the nose point temperature and expanded the range of fastest precipitation temperature.

Complexity analysis of precipitation in changing environment in Chien River Basin,China

The hydrological processes influenced by the multiple factors of climate, geography, vegetation, and human activities are becoming more and more complex, which is an important characteristic of hydrological systems. The different complexity distributions of precipitation processes of the Chien River Basin （a sub-basin of the Minjiang Basin） in two periods （from 1952 to 1980, and from 1981 to 2009） are illustrated using the fractal based on the continuous wavelet transform （CWT）. The results show that （1） at the basin scale the precipitation process in the latter period is more complex than in the former period; （2） the maximum value of the complexity distribution moved from the east to the middle; and （3） through analysis of the time-information and space-information concealed in this complexity change, the precipitation characteristics in the changing environment in the basin can be illuminated. This study could provide a reference for research on disaster pre-warning in changing environments and for integrated water resources management in the local basin.

Complement Protection Against Immune Complex and Acute Glomerulonephritis

in this study serum complement mediated immune complex solubilizing capacity (CMSC) and immune complement precipitation capacity (ICPIC) of 32 children with acute glomerulonephritis (AGN) were measured. The data showed that the level of serum CMSC and ICPIC was markedly decreased in acute phase and returned to normal in the 7th week after onset of disease.Correlation analysis revealed that there were positive correlation between the level of serum CMSC and ICPIC and the serum concentration of CH50, C3, C4, but no linear correlation between the level of serum CMSC and ICPIC and the amount of CIC. These results suggest that the declined serum CMSC and ICPIC in AGN may be associ ated with the pathogenesis of AGN.