Comparison of experimental and predicted TCP solvus temperatures in Ni-base superalloys

Abstract Differential Scanning Calorimetry has been used for the first time to quantify sigma solvus temperatures in a series of model nickel-based alloys. These data were compared with thermodynamic predictions of the sigma solvus temperatures made using Thermocalc software to assess the fidelity of the available databases. It was found that the expected trend of increasing solvus temperature with increasing Mo content is correctly predicted, but that the solvus temperatures themselves are significantly under-predicted. Due to the important role that topologically close-packed phases play in limiting the service life of nickel-based superalloys, this has important implications for the use of sigma solvus temperature predictions in the alloy design process.