Mechanical and high-temperature characterization of additively manufactured Ni-superalloys at SALSA neutron strain diffractometer

Abstract

Neutron diffraction is a well-established method for the measurement and characterization of internal stresses in metallic and ceramic materials at room temperature. Some cases have been reported in the literature in which the method has been extended to higher temperatures. In this paper we report both novel setups for in-situ heat treatments and for in-situ mechanical testing at high temperature at SALSA in the Institut Laue-Langevin (ILL). Characterization of internal stresses in Ni-superalloys demonstrated the feasibility, stability and exploitation of results achieved by a tailored induction heating system. Different coils are adapted to accommodate several sample geometries for accurate focusing of the magnetic heating induction field on the sample, to achieve high heating rates up to 50 °C/s and therefore limiting the microstructural evolution impact during ramping-up to the target temperature. In return, this enhances the choice of reference d0, by either measurements at room temperature and extrapolated values to high temperature, or by direct measurements also at high temperature. A detailed strategy of d0 stress-free reference approaches for such in-situ experiments at high temperature is discussed.