Temperature dependence of single crystal elastic constants in a CoNi-Base alloy: A new methodology

A novel experimental setup combining induction heating, contactless (infrared thermometer) temperature measurements, and custom 15 cm length SiC-tipped piezoelectric transducers has been developed to rapidly collect resonant ultrasound spectroscopy (RUS) data from metallic rectangular parallelepiped (RP) specimens heated in air. This setup is used to collect over 70 of the lowest-frequency resonance modes from a single crystal of the novel CoNi-based superalloy SB-CoNi-10+—an alloy identified for further study due to a promising set of high temperature properties. RUS spectra from room temperature (RT) to 927 °C (1200 K) along with dilatometry measurements of the thermal expansion behavior are supplied to a robust, open-sourced, Bayesian inference code for simultaneous estimation of: three single crystal elastic constants, three crystal axis misorientation parameters, and a noise parameter. This study is the first application of the Bayesian RUS methodology at elevated temperatures, and the first to characterize SB-CoNi-10+. A monotonic decrease in elastic constants (C11,C12,C44) from (236.4, 150.8, 134.1) GPa to (190.7, 138.1, 95.2) GPa and a 15% increase in elastic anisotropy from A = 3.131 → 3.618 is observed upon heating from RT to 927 °C, with an increased rate of softening above 600 °C (873 K).