A portable high-pressure stress cell based on the V7 Paris-Edinburgh apparatus

We describe a new device, based on a V7 Paris-Edinburgh press, for torsional testing of material at pressures up to 7GPa (extendable to 15GPa). Samples are deformed using a simple shear geometry between opposed anvils by rotating the lower anvil, via a rotational actuator, with respect to an upper, stationary, anvil. Use of conical anvil profiles greatly increases sample dimensions more than other high-pressure torsional apparatus did. Samples of polycrystalline Zr (2mm thick, 3.5mm diameter) have been sheared at strains exceeding ≈ 1.5 at constant strain rate and at pressures from 1.8 to 5GPa, and textural development has been studied by electron microscopy. Use of amorphous-boron-epoxy gaskets means that nearly simple shear of samples can be routinely achieved. This apparatus allows study of the plastic and anelastic behaviour of materials under high pressure, and is particularly suited for performing in situ investigations using synchrotron or neutron radiation.