APPLICATIONS OF THERMO-CALC

Aluminum

Thermo-Calc can be used to predict thermophysical and phase-based properties as well as to simulate material behavior throughout the materials life cycle for Aluminum alloys in the 1000 to 8000 series.

Solutions for Aluminum

Aluminum alloys are complex materials that can be broadly grouped into different series (1000 to 8000) depending on the alloying elements that are added. The properties of these alloys are very sensitive to the variation in chemistry, which can be difficult to capture for multicomponent alloys. These properties also strongly depend on the solidification, thermal history, and formation of age-hardened precipitates, of which most are thermodynamically metastable.

Experiments and handbook data cannot take into account all possible variations in chemistry and processing conditions. Thermo-Calc can simulate these effects to fill in data gaps and make predictions of material behavior throughout the materials life cycle.

Calculate the following based on your actual alloy chemistry:

  • Thermophysical properties, such as:
    • Specific heat, enthalpy, latent heat, viscosity, density as a function of temperature, coefficients of thermal expansion, electrical resistivity, and thermal conductivity
    • Phase-based properties, such as:
      • Critical transformation temperatures such as solvus temperatures of stable and metastable precipitates, amounts and compositions of phases, solubility limits, activities, phase diagrams, and more
      • Equilibrium and non-equilibrium solidification, such as:
        • Liquidus, solidus, incipient melt temperatures, freezing range, fraction solid curves, solidification path, fraction eutectic, microsegregation, partition coefficients, latent heat, shrinkage, susceptibility to hot tearing, and more
        • Solutionizing:
          • Optimal homogenization temperatures, time needed to homogenize any chemical segregation arising from solidification, and/or dissolve precipitates
          • Aging:
            • Concurrent nucleation, growth/dissolution, coarsening of precipitate phases, volume fraction, and size distribution as a function of time for both stable and metastable precipitates

Application Examples

Thermo-Calc has many applications to Al-based alloys. Below are three such examples.

Predicting Formation of ꞵ-Al9Fe2Si2 in A3003

The composition specification for A3003, a general purpose Al-Mn alloy, allows for Fe contents up to 0.7wt%. However, at higher iron concentrations, an intermetallic phase, ꞵ-Al9Fe2Si2, can precipitate, which has a detrimental effect on the mechanical properties. Thermo-Calc can be used to predict the stability of ꞵ-Al9Fe2Si2 as a function of alloy chemistry and temperature.

The figure shows that ꞵ-Al9Fe2Si2 is stable over a wide temperature range, and three times as much of this phase forms as the iron content increases from 0.2% to 0.7%. If this phase should be avoided for a certain application, then the iron content needs to be strictly controlled in order to suppress the transformation from α to ꞵ-Al9Fe2Si2.

A heat map showing Fe content influence on formation of detrimental ꞵ-Al9Fe2Si2 phase in A3003 aluminum alloy.

Susceptibility of AA7075 to Hot Tearing

The non-equilibrium freezing range of an alloy can be calculated using the Scheil Solidification Simulation Calculator included in Thermo-Calc and is related to the susceptibility of cast alloys to hot tearing. Typically, the narrower the range, the less susceptible the cast alloy is to hot tearing.

This figure shows the non-equilibrium solidification range of AA7075 compared to a common casting alloy, A356.1. The solidification range of AA7075 is quite large, indicating a higher susceptibility to hot cracking, which is also seen experimentally.

A plot of a Scheil solidification calculation for AA7075 and 356.1 aluminum alloys showing the difference in solidification temperature range.

Predicting Thermophysical Properties of Alloy 356.1

Latent heat release during solidification is a critical value needed for many casting, welding, and additive manufacturing finite element simulations. Typically, handbooks give only a single value for latent heat, whereas in reality the latent heat evolution occurs over the entire solidification temperature range. The evolution of latent heat as a function of chemistry and temperature can be predicted using the Scheil Solidification Simulation Calculator in Thermo-Calc. This temperature dependent data can be used by finite element models for more accurate simulations.

The figure shows the latent heat calculated as a function of temperature for Alloy 356.1.

A plot showing the latent heat during solidification of Alloy 356.1.

Learn more about Applications to Al-based Alloys

An integrated computational materials engineering-anchored closed-loop method for design of aluminum alloys for additive manufacturing

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Improvement of the high-pressure die casting alloy Al-5.7Mg-2.6Si-0.7Mn with Zn addition

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Thermo-Calc Prediction of Mushy Zone in AlSiFeMn Alloys

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