Over the last 50 years, various neutron techniques have been developed to study high-temperature alloys. In particular, the high penetration depth and large cross-section of the neutron beams in combination with different sample environments such as furnaces or testing machinesenable industry-relevant volumetric investigations of alloys [1,2]. Superalloys (or high-performance alloys) are alloys that offer outstanding performance characteristics – excellent corrosion and oxidation resistance, high mechanical strength with good surface stability and the ability to operate in elevated temperature environments. Therefore, in-situ high-temperature experiments are required for such alloys to follow the influence of temperature on phase stability, phase transformation up to dissolution of precipitates. For this task, neutron diffraction (ND) is the best choice to enable characterization of the matrix including the strengthening precipitates and the formation of high-temperature phases. To obtain more information about the precipitates, small-angle neutron scattering (SANS) can be applied to monitor on a larger length scale (nm range) the size and volume fraction of the precipitates with increasing temperature or aging at a certain temperature. During cooling processes, the evolution of precipitate formation can be monitored.
Detecting light elements like hydrogen or boron in minute quantities, down to the ppm range, presents a significant challenge. This is where the neutron-based method known as prompt gamma activation analysis (PGAA) becomes crucial. Incoming neutrons are captured by atomic nuclei of various elements to trigger nuclear excitations to higher energy levels.
The relaxation to the ground-level takes place with characteristic gamma radiation, which enables the elements to be identified. The neutron imaging method (NI) which has a high penetration depth and generally a good signal for light elements, is used to examine macroscopic objects such as cracks or other inhomogeneities (cavities or pores) up to complete turbine blades. Together with standard laboratory equipment such as X-ray diffraction, SEM, TEM, EDS, or APT, an optimal characterization is provided for the alloy development.