The versatile TCS Al-based Alloy Database (TCAL7) is developed for aluminum-based alloys. It can be applied, but is not limited, to the industrial grades. Essentially a thermodynamic database, it also has thermophysical properties data available for molar volume with thermal expansion coefficients, electrical resistivity and thermal conductivity of all phases, as well as viscosity and surface tension of liquid. Dr. Hai-Lin Chen, Database Developer at Thermo-Calc Software, describes the multiple advantages of TCAL7.
A Thermodynamic Database with Thermophysical Properties
TCAL7 can be used as a conventional CALPHAD thermodynamic database for predicting phase formation, phase amounts and phase compositions during casting and heat treatments. Additionally, one can use it to calculate various thermodynamic properties, such as heat capacity, energy of formation, reaction heat and driving force.
Together with the compatible atomic TCS Aluminum Mobility Database (MOBAL5), TCAL7 can be used for kinetic simulations. With the Diffusion Module (DICTRA),
one can simulate diffusion-controlled transformations, for instance for studying homogenization of matrix phase and dissolution of grain boundary particles. TCAL7 and MOBAL5 can also simulate concurrent nucleation, growth and coarsening during multi-particle precipitation with the Precipitation Module (TC-PRISMA). One can generate important data, such as critical radius of nuclei, particle size distribution, number density and their evolution. These kinds of simulations are perfect for designing aging treatments and in principle may also be employed to the early stage of solidification.
TCAL7 supports calculating the aforementioned thermophysical properties and deriving properties related to them, either for individual phases or for specific alloys. This provides more necessary data for material design and process optimization. For instance, the molar volume data allow us to evaluate alloy density, casting shrinkage, lattice mismatch of a precipitate with the matrix phase. Thermal conductivity can be used for deriving thermal resistivity and thermal diffusivity, and electrical resistivity for electrical conductivity. As an example, thermal conductivity is one of the key factors which is needed for optimizing additive manufacturing.
Aluminum Alloy Composition Design and Process Design for Industry and Academia
TCAL7 is developed for aluminum alloys of industrial relevance, from 1000 series to 8000 series. Anyone working on aluminum alloy composition design and process design would benefit from using TCAL7.
Aluminum Alloy Casting
TCAL7 and its predecessors have been widely employed to aluminum alloys casting simulations. As a quick investigation, an equilibrium stepping calculation and a Scheil simulation provide the upper and lower boundaries of the solidification interval, and a real solidification under normal conditions is expected to fall between them. If the cooling rate is known, or can be estimated, Scheil simulations can be performed in a more accurate way, considering the diffusion in solid phases with the back-diffusion module. Solidification simulations predict not only the formation of grain boundary phases, but also the extent of composition segregation in the (Al) grains. To some extent, the information on phase transformation even allows us to interpret microstructure formation in as-cast alloys and to evaluate their castability, such as hot tearing susceptibility.
Benefits of TCAL7 in Various Heat Treatments
The heating temperature can be provisionally determined with a stepping calculation. The Diffusion Module (DICTRA) simulations can be run with TCAL7 and MOBAL5 for dissolution of particles. Such simulations help to optimize the heating temperature, and to estimate the heating time which is needed for the particles to be fully dissolved into the (Al) matrix, or to reach the maximum extent of the solution. Diffusion Module (DICTRA) simulations can also be performed to approximate the particle size distribution. The initial particle fraction can be either measured with experiments or estimated with solidification simulations.
The Diffusion Module (DICTRA) simulations can provide detailed composition profiles for the (Al) grains at specific time during the homogenization, whether the heating is isothermal, isochronal, stepwise or even more complex procedures. They help to optimize the heating temperature and estimate the holding time. The initial composition profile can be either measured with experiments or estimated with simulations.
Most important metastable precipitates in aluminum alloys have been modeled in TCAL7. TCAL7 and MOBAL5 can be used with the Precipitation Module (TC-PRISMA) to simulate multi-particle precipitation during aging. This provides for example the evolution of particle size distribution and number density with the aging time. The simulations can be run by considering aspect ratio, so that the morphology change may be tentatively predicted.
Recycling of Aluminum Scrap
As demonstrated in the publication Development and applications of the TCAL aluminum alloy database, it helps to choose the recycling route and design the recycling process of specific types of scrap. One of the highlights in those examples is that CALPHAD calculations can easily predict the Fe removal fraction. It can quickly optimize the processing temperature and the addition of alloying element.
The TCAL7 TCS Al-based Alloy Database is available with a host of calculation and validation examples. For further information, contact firstname.lastname@example.org.