Liquidus temperature determination in multicomponent alloys by thermal analysis

Abstract

Thermal analysis is often used to determine equilibrium phase boundary temperatures such as the liquids. Accurate measurements require proper calibration procedures, which are standard for given instruments. In multicomponent alloys such as RENE N5 and PWA 1484 superalloys, a complex melting behavior associated with the solidification structure was exposed by examining the melting response at different heating rates. The observed variability in the melting signal is related to the sample processing history and is not addressed by the various standard calibration methods or supplemental procedures for different heating rates. The liquidus temperature can be determined under conditions approaching full compositional equilibrium by the application of an interrupted-heating thermal analysis protocol. The approach provides a new strategy for the reliable determination of phase boundary temperatures by thermal analysis.