APPLICATIONS OF THERMO-CALC

Failure Analysis

Thermo-Calc can complement post-failure testing and microstructural analysis by giving insight into how the chemical composition and thermal history can affect the material properties and behavior.

Applications to Failure Analysis

Materials can fail for a number of different reasons. Sometimes the reason for those failures can be attributed to an underlying aspect of the chemistry of the material, for example the formation of a deleterious phase, a life limiting phase, a lower than expected phase transformation temperature, chemical interaction at a joint forming a brittle phase, large differences in volumetric expansion, and so on.

Thermo-Calc can complement post-failure testing and microstructural analysis by giving insight into the potential influence of chemical changes on the failure and how changes to the composition or processing conditions can be made to avoid such failures in the future.

Thermo-Calc can be used as part of a failure analysis investigation by making calculations that:

  • Identify phases on fracture surfaces by coupling chemical composition data with thermodynamic calculations
  • Predict the formation of deleterious phases that lead to premature failure
  • Simulate the kinetics of formation of potential life limiting phases under a range of operating conditions
  • Determine coefficients of thermal expansion (CTE) mismatch
  • Predict the formation of phases at the joins of dissimilar metals

Application Examples

Thermo-Calc has many applications to failure analysis. Below is one such example.

Supplanting SEM/EDS with Thermo-Calc to Understand Failure Mechanisms

Root cause failure analysis often requires quantifying phases or precipitates on fracture surfaces. However, advanced sample extraction and characterization techniques, for instance Focused Ion Beam (FIB) and Transmission Electron Microscopy (TEM), can be difficult to access. More common techniques like Scanning Electron Microscopy (SEM)/ Energy Dispersive Spectroscopy (EDS) can only give qualitative results when the surface is not flat or the particles are less than 1 µm in diameter. Coupling qualitative EDS information with a Thermo-Calc calculation gives a clearer picture of the failure mechanism.

This SEM backscatter image shows a solidification crack in a Ni-based alloy weld metal. The particles are enriched in Titanium, based on EDS scans. Thermo-Calc predicts that a eutectic γ+Ti(C,N) forms at the end of solidification, likely leading to cracking in this alloy.

An SEM backscatter image showing a solidification crack in a Ni-base weld metal.

Learn more about Applications to Failure Analysis

Failure and fracture analysis of a high-alloy Ni-Al bronze chain connector of a tube drawing machine

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