APPLICATIONS OF THERMO-CALC

Titanium and TiAl

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 a wide range of Ti and TiAl alloys.

Solutions for Titanium / TiAl Alloys

For applications requiring good corrosion resistance, high temperature specific strength, and toughness, titanium and titanium aluminide alloys are commonly used. The properties of these alloys are very sensitive to the variation in chemistry, especially oxygen, which can be difficult to capture for multicomponent alloys. Titanium alloy properties also strongly depend on thermo-mechanical processing around the beta transus temperature, which is also sensitive to chemistry. 

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:
    • Specific heat, enthalpy, latent heat, density as a function of temperature, and coefficients of thermal expansion
    • Phase-based properties:
      • Critical transformation temperatures such as β transus, α transus, α2+γ eutectoid, and α/β T0 line
        • Solvus temperatures and volume fractions of phases such as Laves phase, α2-Ti3Al, B2, and Ti5Si3
          • Partitioning of alloying elements between α and β, solubility limits, and phase diagrams
          • Equilibrium and non-equilibrium solidification:
            • Liquidus, solidus, incipient melt temperatures, freezing range, fraction solid curves, solidification path, fraction eutectic, microsegregation, partition coefficients, latent heat, shrinkage, and more
            • Homogenization:
              • Optimal homogenization temperatures, time needed to homogenize any chemical segregation arising from solidification, and/or dissolve precipitates
              • Precipitation hardening:
                • Concurrent nucleation, growth/dissolution, coarsening of precipitate phases, volume fraction, and size distribution as a function of time
                • Surface hardening:
                  • Nitriding kinetics of Ti alloys

Application Examples

Thermo-Calc has many applications to Ti- and TiAl-based alloys. Below are two such examples.

Calculate Beta Approach Curves

The β-transus temperature in titanium alloys plays an important role in the design of thermo-mechanical treatments. It primarily depends on the chemical composition of the alloy and is sensitive to the actual alloy chemistry. The oxygen content also has a big effect on the stability of the alpha phase. A beta approach curve shows the fraction of beta phase as a function of temperature and is useful when designing heat treatments to obtain specific properties.

This figure shows a beta approach curve for a Ti-6-2-4-2 alloy calculated in Thermo-Calc along with experimental data from Semiatin et al., Metall. Mater. Trans. A, vol. 38, no. 4, pp. 910–921, 2007.

A plot showing the Beta approach curve for Ti-6-2-4-2 alloy.

Predict Phase Balance as a Function of Cooling Rate

There is an inherent relationship between the material microstructure and the final material properties of a component. In titanium alloys, the balance of alpha/beta phases plays a major role in determining the final mechanical, corrosion, and creep properties. This phase balance can vary as a function of cooling rate. Thermo-Calc can simulate phase balance and precipitation behavior as a function of thermal history.

This figure shows the simulated amount of alpha phase in Ti-6Al-4V alloys as a function of cooling rate from 950 °C using the Diffusion Module (DICTRA) (recalculated based on data from Martukanitz et al., Addit. Manuf., vol. 1–4, pp. 52–63, 2014). The final amount of alpha is reduced as the cooling rate is increased.

A plot showing the phase balance in Ti-6Al-4V as a function of different cooling rates.

Learn more about Applications to Ti/TiAl-based Alloys

Next Generation TiAl Alloys Advanced by New European Consortium

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Electron Beam Melting of a β‐Solidifying Intermetallic Titanium Aluminide Alloy

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Design of High Temperature Ti–Al–Cr–V Alloys for Maximum Thermodynamic Stability Using Self-Organizing Maps

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