Improving CALPHAD applications to process optimization for aluminum alloys

Hai-Lin Chen Qing Chen1

1 Thermo-Calc Software AB, Rasundavagen 18, SE-169 67 Soina, Sweden

EXTENDED ABSTRACT: CALPHAD calculations have been widely employed for materials design and process optimization of aluminum alloys. The accuracy and the versatility of the calculations depend on the quality and the completeness of the databases. TCAL8 is a thermodynamic database specifically for aluminum alloys. It contains well-assessed descriptions for all the core systems as well as many systems involving minor alloying elements. TCAL8 includes not only all the stable phases in each assessed system, but also important aging hardening precipitates that form in the industrial grades of aluminum alloys. Figure 1 illustrates a number of modelled phases, which are of critical importance to the 7000 series. TCAL8 has been used fbr not only calculating phase equilibria, but also predicting phase formation in non-equilibrium processes, such as casting and heat treatments, as well as thixoforming and recycling, etc. [1]. TCAL8 can be used in conjunction with the atomic mobility database MOBAL7 fbr kinetic simulations, such as homogenization, particle dissolution, back difiusion during solidification, and precipitation during aging, etc. [1-3]. It contains descriptions of molar volume and thermal expansivity, electrical resistivity and thermal conductivity of liquid and all the solid phases, as well as viscosity and surface tension of liquid. This work is to demonstrate the applications of the CALPHAD approach to the research on aluminum alloys with start-of^the-art databases and tools: Scheil simulations fbr predicting phase formation during solidification; evaluation of physical properties in the liquid, semi-solid and as-solidified states; evaluation of castability, such as casting shrinkage and susceptibility to hot tearing, equilibrium calculations and DICTRA simulations fbr optimizing the temperature and time of solution treatments; systematical precipitation simulation of age-hardening particles to account fbr their fraction, size, number density and composition; prediction of thermophysical properties fbr non-equilibrium and inhomogeneous as-cast alloys, tempered alloys and aged alloys with the most recently developed models and tools.

KeywordsCALPHAD; phase formation; thermophysical properties;


[1] H.-L. Chen, Q. Chen and A. Engstrom, CALPHAD, 62, (2018) 154-171

⑵ J.O, Andersson, et al., Calphad, 26, (2002) 273-312

[3] H.-L. Chen, et al., Mater. Today Proc., 2, (2015) 4939Y948.

Brief Introduction of Speaker
Hai-Lin Chen

Hai-Lin Chen received his PhD from Central South University and worked as a Postdoctoral associate at Clausthal University (Germany). He has worked at Thermo-Calc Software for 11 years and was the principal developer and project leader of the start-of-the-art databases for light metals and alloys, TCAL, TCMG, and the first version of TCTL He recently worked on the models for and the modeling of electrical resistivity and thennal conductivity of metals and alloys. He is now a Senior Research Scientist of Forward Research and AI/ML at the Dept, of Research and Innovation.