Failure analysis

Materials can fail for a number of different reasons and 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 and so forth.

Software tools, such as Thermo-Calc, can complement post-failure testing, microstructural analysis, etc., in order to give better insight into the potential influence of chemical changes on the failure and insight into how chemical changes to the composition or processing conditions can be made to avoid such failures in the future.

Some examples include:

Thermo-Calc

  • Understanding an alloy or material in terms of composition variation and temperature on the phases formed, the amounts of those phases and the temperatures over which they are stable can give huge insight into failures. The presence of a deleterious phase, even in small amounts, or the unexpected lowering (or increasing) in a phase transformation temperature, even with well characterized materials, can have catastrophic effects.
  • Predictions are often made around nominal chemistries, but how the precipitate phases change with allowable variations in the chemistry of an alloy can also give rise to large variations in performance. It can be difficult to capture this experimentally, particularly long tail effects, so computations can give further insight into this.
  • Predicting the stability of materials in their in-service environments at operational conditions and potential extremes that could give rise to failures.

Diffusion module (DICTRA)

  • Gaining insight into the role of segregation of impurity elements to grain boundaries and the in-service formation of thin film precipitates on the grain boundaries as important contributors to failure mechanisms.
  • Simulating growth and dissolution of precipitate phases.
  • Predicting the kinetics of the degradation of e.g. coatings through reactions with substrate material or the environment.

Precipitation module (TC-PRISMA) 

  • Predicting nucleation and growth of slow precipitating life limiting phases to feed into life prediction models.