APPLICATIONS OF THERMO-CALC

Zirconium

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 Zirconium alloys.

Solutions for Zirconium

Zirconium alloys exhibit excellent resistance to corrosive attack in most organic and inorganic acids, salt solutions, strong alkalis, and some molten salts. Such properties make them suitable for use in the chemical, oil, and gas industries. Furthermore, their biocompatibility also makes them suitable for body implants, and their low thermal neutron cross section leads to their use in nuclear reactors for the cladding of fuel rods.

Understanding the material properties and behavior of Zirconium alloys, particularly as a function of chemistry, is therefore important. Unfortunately, much of the available data is based on limited experimental datasets. Where this data is missing, Thermo-Calc can be used to generate the materials property data 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, density as a function of temperature, coefficients of thermal expansion, viscosity, and surface tension of liquid
    • Phase based properties, such as:
      • Critical transformation temperatures (including their sensitivity to oxygen), 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, and more

Application Examples

Thermo-Calc has many applications to Zr-based alloys. Below are two such examples.

Oxygen Impact on Phase Equilibria and Transition Temperatures

Oxygen is one of the major impurities in Zr-based alloys and has a strong influence on the α/β transus temperature and corresponding phase compositions. Thermo-Calc can be used to predict the sensitivity of varying amounts of oxygen on the α/β transus temperature for different alloy chemistries. 

The figure here shows a comparison of calculated values with experimental data of HUN where α+β →β transition temperatures were measured at different oxygen levels in the Zr-rich region. As can be seen, the calculation results are in good agreement with the experimental ones.

A plot showing the comparison of calculated values with experimental data of HUN where α+β →β transition temperatures were measured at different oxygen levels in the Zr-rich region.

Hydrogen Impact on Phase Equilibria and Transition Temperatures

The oxidation of zirconium by water releases hydrogen gas, which partly diffuses into the alloy. As this occurs, an increase of hydrogen in solid solution results in a lowering of the α/β transus temperatures and, if the solubility limit is exceeded, also leads to the formation of zirconium hydrides. These hydrides are less dense and are weaker mechanically than the alloy and so their formation results in blistering and cracking of the cladding – a phenomenon known as hydrogen embrittlement. 

Thermo-Calc can be used to predict the sensitivity of different alloy chemistries to hydrogen, as can be seen in the figure here, which shows the calculated H solubility in HCP_Zr compared with published experimental data from Zuzek et al. (Bulletin of Alloy Phase Diagrams, 1990).

A plot showing the calculated H solubility in HCP_Zr compared with published experimental data from 1990Zuz.

Learn more about Applications to Zr-based Alloys

A collection of examples that demonstrate the validity and calculation abilities of the TCZR database.

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