RHEGAL: Resistive heating gas enclosure loadframe for neutron scattering.

neutron scattering is a powerful tool to reveal materials atomic structural response such as phase transformation, lattice straining, and texture under external stimuli. The advent of a high flux neutron source such as the Spallation Neutron Source (SNS) allows fast measurement in even non-equilibrium conditions, i.e., phase transformation in steels. However, the commercial fast heating apparatus such as commercial physical simulation equipment is not designed for neutron scattering, which limits its application to materials research by using neutrons. Here we present a resistive heating gas enclosure loadframe (RHEGAL) for non-equilibrium phase transformation studies by using neutron scattering, which takes the advantage of high flux neutron sources like SNS. RHEGAL enables fast resistive heating of metal samples to 1200 °C at a rate up to 60 °C/s in an inert atmosphere. It provides both horizontal and vertical positions for scattering optimization. The mechanical loading capability also allows high temperature tension above the oxidation temperature limit. The optimized translucent neutron scattering window by silicon allows both reflection and transmission measurements, making this equipment applicable for neutron diffraction, small angle scattering, and imaging. To demonstrate the fast heating capability, the phase transformations of an example of advanced high strength steel heated at 3 °C/s and 30 °C/s were measured with the VULCAN engineering diffractometer, and the different phase transformation kinetics by neutron diffraction were presented.