Sino German Cooperation Group Microstructure in Al Alloys

Changsha, China

Sino German Cooperation Group Microstructure in Al Alloys

Changsha, China
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Xin J.,Central South University | du Y.,Central South University | du Y.,Sino German Cooperation Group Microstructure in Al alloys | Shang S.,Pennsylvania State University | And 4 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2016

A new relationship among self- and impurity diffusion coefficients has been proposed for binary solution phases and verified via 30 solid solutions. In terms of this model, one impurity diffusion coefficient in a binary phase can be predicted once the other three diffusion coefficients are available. The application of the present model is exemplified in the Al-Mg system. © 2016 The Minerals, Metals & Materials Society and ASM International

Chen W.,Central South University | Chen W.,Sino German Cooperation Group Microstructure in Al Alloys | Zhang L.,Central South University | Zhang L.,Sino German Cooperation Group Microstructure in Al Alloys | And 3 more authors.
Philosophical Magazine | Year: 2014

Viscosity and diffusivity, two important transport coefficients, are systematically investigated from unary melt to binary to multicomponent melts in the present work. By coupling with Kaptays viscosity equation of pure liquid metals and effective radii of diffusion species, the Sutherland equation is modified by taking the size effect into account, and further derived into an Arrhenius formula for the convenient usage. Its reliability for predicting self-diffusivity and impurity diffusivity in unary liquids is then validated by comparing the calculated self-diffusivities and impurity diffusivities in liquid Al- and Fe-based alloys with the experimental and the assessed data. Moreover, the Kozlov model was chosen among various viscosity models as the most reliable one to reproduce the experimental viscosities in binary and multicomponent melts. Based on the reliable viscosities calculated from the Kozlov model, the modified Sutherland equation is utilized to predict the tracer diffusivities in binary and multicomponent melts, and validated in Al-Cu, Al-Ni and Al-Ce-Ni melts. Comprehensive comparisons between the calculated results and the literature data indicate that the experimental tracer diffusivities and the theoretical ones can be well reproduced by the present calculations. In addition, the vacancy-wind factor in binary liquid Al-Ni alloys with the increasing temperature is also discussed. Whats more, the calculated inter-diffusivities in liquid Al-Cu, Al-Ni and Al-Ag-Cu alloys are also in excellent agreement with the measured and theoretical data. Comparisons between the simulated concentration profiles and the measured ones in Al-Cu, Al-Ce-Ni and Al-Ag-Cu melts are further used to validate the present calculation method. © 2014 © 2014 Taylor & Francis.

Xin J.,Central South University | Xin J.,Sino German Cooperation Group Microstructure in Al Alloys | Zhang W.,Central South University | Zhang W.,Sino German Cooperation Group Microstructure in Al Alloys | And 8 more authors.
Computational Materials Science | Year: 2014

The diffusivities in fcc phase of the Al-Cu-Mg system are systematically predicted via first-principles calculations coupled with CALPHAD (CALculation of PHAse Diagram) technique. All the self-and impurity diffusion coefficients of fcc phase in this ternary system, including both stable and meta-stable states, are calculated via first-principles calculations. The enthalpy of vacancy formation and migration, binding enthalpy of vacancy-solute, entropy of vibration, effective atomic jump frequency, as well as the pre-factors and activation energies for diffusion in the Arrhenius equation are obtained. The atomic mobilities of the three elements are then obtained based on the first-principles calculated diffusion coefficients. Moreover, the interdiffusion coefficients of the Al-Cu, Al-Mg and Cu-Mg binary systems are calculated by means of the DICTRA (DIffusion-Controlled TRAnsformation) package in the framework of CALPHAD approach. Comprehensive comparisons between the predicted and measured diffusivities show that most of the experimental data can be well reproduced. It is found that the combination of first-principles calculations and CALPHAD technique is an effective strategy to obtain diffusivities for multicomponent systems. © 2014 Elsevier B.V. All rights reserved.

Chen W.-M.,Central South University | Chen W.-M.,Sino German Cooperation Group Microstructure in Al Alloys | Zhang L.-J.,Central South University | Zhang L.-J.,Sino German Cooperation Group Microstructure in Al Alloys | And 3 more authors.
Journal of Electronic Materials | Year: 2014

The recently developed Arrhenius formula for the modified Sutherland equation was employed to calculate the self- and impurity diffusivities in liquid Sn, Ag, and In. The reliability of the calculated self- and impurity diffusivities was validated by comparing the presently calculated results with critically reviewed literature data. Based on reliable tracer and chemical diffusivities available in literature, the atomic mobility parameters in Sn-Ag and Sn-In melts were then evaluated with the aid of the available thermodynamic description for the liquid phase. Comprehensive comparisons showed that most of the measured and theoretical diffusivities in Sn-Ag and Sn-In melts can be reasonably reproduced by the currently obtained atomic mobilities. Moreover, the atomic mobilities were further verified by comparing the model-predicted concentration profiles with the measured ones in various liquid Sn-In diffusion couples. In addition, a simulation of Ag dissolution into liquid Sn-Ag solder during a reflow process was performed via the presently obtained atomic mobilities in the Sn-Ag melt. © 2014 TMS.

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