Design and operating characteristic of a vacuum furnace for time-of-flight inelastic neutron scattering measurements

We present the design and operating characteristics of a vacuum furnace used for inelastic neutron scattering experiments on a time-of-flight chopper spectrometer. The device is an actively water cooled radiant heating furnace capable of performing experiments up to 1873 K. Inelastic neutron scattering studies performed with this furnace include studies of phonon dynamics and metallic liquids. We describe the design, control, characterization, and limitations of the equipment. Further, we provide comparisons of the neutron performance of our device with commercially available options. Finally we consider upgrade paths to improve performance and reliability

Design and operating characteristic of a vacuum furnace for time-of-flight inelastic neutron scattering measurements

We present the design and operating characteristics of a vacuum furnace used for inelastic neutron scattering experiments on a time-of-flight chopper spectrometer. The device is an actively water cooled radiant heating furnace capable of performing experiments up to 1873 K. Inelastic neutron scattering studies performed with this furnace include studies of phonon dynamics and metallic liquids. We describe the design, control, characterization, and limitations of the equipment. Further, we provide comparisons of the neutron performance of our device with commercially available options. Finally we consider upgrade paths to improve performance and reliability

Deformation characteristics of the intermetallic alloy 60NiTi

The deformation behavior of a Ni-rich Ni55Ti45 (at.%) alloy, commonly known as 60NiTi (as designated inwt.%), was analyzed using neutron and synchrotron x-ray diffraction during in situ isothermal tensionand compression loading, and pre and post-test electron microscopy. The alloy was shown to exhibitremarkable strength and high hardness resulting from a high density of fine Ni4Ti3 precipitates (size~67 nm), which were uniformly dispersed throughout the matrix after a solution treatment and oilquench. The precipitate volume fraction was 55 ± 3%, determined from both the neutron Rietveldrefinement and conventional x-ray measurements. Non-linear stress-strain behavior was observed intension (but not in compression) and was attributed to reversible stress-induced martensite (SIM) thatforms to accommodate the stress as revealed by neutron diffraction measurements. The tensile andcompressive neutron data also showed peak broadening and residual lattice strains. Transmission andscanning electron microscopy revealed stress-induced coarsening of Ni4Ti3 precipitates in both tensionand compression tested samples, but precipitation and growth of the stable Ni3Ti phase was observedonly after tensile testing. Finally, the potential ramifications of these microstructural changes arediscussed

Design and implementation of a multiaxial loading capability during heating on an engineering neutron diffractometer

A gripping capability was designed, implemented, and tested for in situ neutron diffraction measurements during multiaxial loading and heating on the VULCAN engineering materials diffractometer at the spallation neutron source at Oak Ridge National Laboratory. The proposed capability allowed for the acquisition of neutron spectra during tension, compression, torsion, and/or complex loading paths at elevated temperatures. The design consisted of age-hardened, Inconel (R) R 718 grips with direct attachment to the existing MTS load frame having axial and torsional capacities of 100 kN and 400 N m, respectively. Internal cooling passages were incorporated into the gripping system for fast cooling rates during high temperature experiments up to similar to 1000 K. The specimen mounting couplers combined a threaded and hexed end-connection for ease of sample installation/removal without introducing any unwanted loads. Instrumentation of this capability is documented in this work along with various performance parameters. The gripping system was utilized to investigate deformation in NiTi shape memory alloys under various loading/control modes (e.g., isothermal, isobaric, and cyclic), and preliminary results are presented. The measurements facilitated the quantification of the texture, internal strain, and phase fraction evolution in NiTi shape memory alloys under various loading/control modes