Damage nucleation during transverse creep of a directionally solidified Ni-based superalloy

Abstract

A directionally solidified Ni-based superalloy DS200 is investigated under low (750 °C) and high temperature (900 °C) transverse creep. In-situ creep tests with strain measurements are performed to capture creep strain evolution in the individual crystallographic grains. Moreover, the microstructure configurations that promote damage nucleation are identified as a function of the loading condition. High angle grain boundaries are the preferred sites for crack nucleation under all investigated loading conditions. However, grain boundary configurations promoting crack nucleation are observed to significantly differ as a function of the loading conditions. Such observations are discussed in view of creep behavior and damage processes.