For more than 50 years, observations of earthquakes to depths of 100 to 650 kilometers inside Earth have been enigmatic: at these depths, rocks are expected to deform by ductile flow rather than brittle fracturing or frictional sliding on fault surfaces Laboratory experiments and detailed calculations of the pressures and temperatures in seismically active subduction zones indicate that this deep-focus seismicity could originate from dehydration and high-pressure structural instabilities occurring in the hydrated part of the lithosphere that sinks into the upper mantle Thus, seismologists may be mapping the recirculation of water from the oceans back into the deep interior of our planet

https://science.sciencemag.org/content/sci/252/5002/68.full.pdf

Deep-focus earthquakes and recycling of water into the earth's mantle

Thermally- and stress-induced thermoelastic martensitic transformations in the reference frame of equilibrium thermodynamics

Size effects in shape memory alloy microwires

Stress‐strain trajectories associated with pseudoelastic behavior of a Cu‐19.4 Zn‐13.1 Al (at. %) single crystal at room temperature have been determined experimentally. For a constant cross‐head speed the trajectories and the associated hysteresis behavior are perfectly reproducible; the trajectories exhibit memory properties, dependent only on the values of return points, where transformation direction is reverted. An adapted version of the Preisach model for hysteresis has been implemented to predict the observed trajectories, using a set of experimental first‐order reversal curves as input data. Explicit formulas have been derived giving all trajectories in terms of this data set, with no adjustable parameters. Comparison between experimental and calculated trajectories shows a much better agreement for descending than for ascending paths, an indication of a dissymmetry between the dissipation mechanisms operative in forward and reverse directions of martensitic transformation.

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Preisach modeling of hysteresis for a pseudoelastic Cu-Zn-Al single crystal

The mechanism of diffusion-free (thermoelastic) martensitic transitions in solids is theoretically examined using a thermodynamic approach together with a self-consistent-field order parameter model. Based on the resulting equations, a theory of smeared martensitic transitions is constructed as a kinetic equilibrium theory of heterophase structures which takes into account heterogeneous martensite nucleation and the interaction of interphase boundaries with various types of structural defects in real materials. An extensive comparison is made between the theoretical predictions and the experimental data on thermoelastic martensitic transformations in alloys with shape memory. The universal nature of the theory of diffuse first-order phase transitions is illustrated by applying it to ferroelectric and ferroelastic transitions in some classical ferroelectric and high-temperature superconductors.

M. Rosen

Papers

On the nature of the thermoelastic martensitic phase transformation in Au-47.5 at.% Cd determined by acoustic emission