In-situ neutron diffraction during stress relaxation of a single crystal nickel-base superalloy

The stress relaxation behaviour of a single crystal nickel-base superalloy has been quantified using time-of-flight neutron diffraction analysis for a range of temperatures relevant to casting. A new iterative analysis methodology is described to isolate the lattice strain behaviour of the γ matrix and γ' precipitate phases from data obtained sufficiently rapidly to help elucidate the microscopic effect of macroscopic stress relaxation. The independent response of γ and γ' is revealed, showing the temperature sensitivity of lattice strain relaxation. The γ/γ' response is discussed in the context of thermo-mechanical conditions that may affect the propensity for recrystallisation.