In-situ study and simulation of incipient melting of single crystal superalloy

Nils Warnken, Xu Chen, Eric Balestra, Carl Slater

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Directionally solidified single crystal superalloys commonly exhibit significant levels of microsegregation, which makes solution heat treatments necessary. In order to avoid incipient melting during the heat treatment, temperature is commonly ramped up in a slow fashion allowing diffusion to partially homogenise the structure. This however is adding a lot of time to the heat treatment. This work aims at developing a better understanding of the kinetics of incipient melting and its link to the microstructure inherited from solidification processing.
Samples CMSX-4 that were produced via directional solidification at different rates were rapidly heated under protective Ar-atmosphere within the hot-chamber of a confocal-laser-scanning microscope (CSLM). The onset of melting and the development of the melt pool was directly observed, while the temperature of the sample was measured using a thermocouple placed underneath the crucible. Thermodynamic calculations using the Scheil model within ThermoCalc were used and additionally microstructure evolution was simulated using the phase-field software MICRESS.
The experiments show that melt pools form in the interdentritic region and spread along dendrite boundaries before extending into dendrites. The fraction-liquid vs. temperature profile obtained from CSLM and MICRESS simulations both show deviation from the Scheil curve upon melting.
Original languageEnglish
Title of host publicationSolidification Processing 2017
Subtitle of host publicationProceedings of the 6th Decennial International Conference on Solidification Processing
EditorsZhongyun Fan
PublisherBrunel University
ISBN (Print)978-1908549297
Publication statusPublished - 25 Jul 2017
Event6th Decennial International Conference on Solidification Processing - Beaumont Estate, Old Windsor, United Kingdom
Duration: 25 Jul 201728 Jul 2017


Conference6th Decennial International Conference on Solidification Processing
Abbreviated titleSP17
Country/TerritoryUnited Kingdom
CityOld Windsor
Internet address


  • Incipient melting
  • Single crystal superalloy
  • Confocal laser scanning microscope
  • Phase-field simulation


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