In situ deformation apparatus for time-of-flight neutron diffraction:Texture development of polycrystalline ice Ih

Abstract

This article documents a new in situ deformation apparatus built for neutron diffraction investigations of polycrystalline materials in low-temperature environments and the first experiment in which it was used. We performed texture analysis of fine-grained polycrystalline D2O ice Ih deformed uniaxially between 230 and 240K using time-of-flight neutron diffraction on the high-pressure preferred orientation diffractometer at the Manuel Lujan, Jr. Neutron Scattering Center at Los Alamos National Laboratory. The new deformation apparatus operates at 1atm of ambient pressure and over temperatures in the range of 77K<T<298K, and accommodates up to 667N of uniaxially applied load. It is suitable for diffraction studies of any bulk polycrystalline material, ideally cylindrical in shape, and is adaptable to multiple neutron spectrometers, including those at other polychromatic and monochromatic neutron facilities. The first experiment on a hexagonal ice sample demonstrates development of fiber texture in the direction of the applied load. The equipment has many applications to earth science, glaciology, and ice engineering.

The influence of strain rate and presence of dispersed second phases on the deformation behaviour of polycrystalline D2O ice

“…All experiments (Table 2) have used a matrix of deuterated ice (D 2 O), as this allows quantitative in situ neutron diffraction and grain size analysis during deformation. D 2 O has the same crystal structure, similar mechanical properties, and deformation behaviour as H 2 O ice (Petrenko and Whitworth, 1999; McDaniel and others, 2006; Wilson and others, 2014; Middleton and others, 2017). Undeformed samples of deuterated ice were prepared by crushing and mixing 180–250 µm sieved ice particles with liquid D 2 O at −10 to −5°C within moulds.…”

The effect of rock particles and D 2 O replacement on the flow behaviour of ice

“…D 2 O ice is used as a replacement for H 2 O in experiments carried out in neutron beamlines (e.g. [23][24][25][26][27]), where replacement of H 2 O by D 2 O is necessary to avoid incoherent scattering of the diffracted beam [28,29]. These in situ studies have allowed the evolution of texture during deformation to be observed, and grain-scale changes linked to the dominant deformation mechanism to be identified [26].…”

Rietveld texture analysis from TOF neutron diffraction data

“…The information derived from the diffraction data is averaged over a large volume ͑typically in the order of a cubic centi-meter͒; therefore, sampling statistically significant numbers of grains even in coarse-grained aggregates and special sample environments are possible. Time-of-flight ͑TOF͒ neutron diffraction is increasingly used to record textures of bulk materials, providing the additional advantage of determining textures of low symmetry phases ͑e.g., Brown et al, 2006;Xie et al, 2003͒, of composites with complex diffraction patterns ͑e.g., Ivankina et al, 2005;Wenk et al, 2001͒, or in situ experiments at high/low temperature ͑e.g., Bhattacharyya et al, 2006;Lonardelli et al, 2007;McDaniel et al, 2006;Wenk et al, 2007͒ andstress ͑Hartig et al, 2006͒. Since the Rietveld approach ͑Rietveld, 1969͒ is used to extract the texture information, it does not rely on single wellresolved diffraction peaks, as pole figure gonio metersdo, which are used for constant wavelength neutrons or X-rays. Neutron diffraction is most efficient with multidetector spectrometers such as high pressure preferred orientation ͑HIPPO͒ ͑at LANSCE, Los Alamos; Vogel et al, 2004;Wenk et al, 2003͒, GEM ͑at ISIS, U.K.;Day et al, 2004͒, or SKAT ͑at the Joint Institute for Nuclear Research, Russia; Ullemeyer et al, 1998͒, where each detector records a spectrum of crystals with lattice planes in reflection orientation.…”