Martensitic transformation was successfully introduced to bulk metallic glasses as the reinforcement micromechanism. In this Letter, it was found that the twinning property of the reinforcing crystals can be dramatically improved by reducing the stacking fault energy through microalloying, which effectively alters the electron charge density redistribution on the slipping plane. The enhanced twinning propensity promotes the martensitic transformation of the reinforcing austenite and, consequently, improves plastic stability and the macroscopic tensile ductility. In addition, a general rule to identify effective microalloying elements based on their electronegativity and atomic size was proposed.

Microscopic polar clusters can play an important role in the phase transition of ferroelectric perovskite oxides such as BaTiO 3 , which have shown coexistence of both displacive and order-disorder dynamics, although their topological and dynamical characteristics are yet to be clarified. Here, we report sharp increases in the widths and intensities of Bragg peaks from a BaTiO 3 single crystal, which are measured in situ during cooling/heating within a few degrees of its phase transition temperature T C , using a neutron time-of-flight Laue technique. Most significantly a sharper and stronger increase in peak widths and peak intensities were found to occur during cooling than that during heating through T C . A closer examination of the Bragg peaks revealed their elongated shapes in both the paraelectric and ferroelectric phases, the analysis of which indicated the presence of microdomains that have correlated <111>-type polarization vectors within the {110}-type crystallographic planes. No significant increase in the average size of the microdomains (~10 nm) near T C could be observed from diffraction measurements, which is also consistent with small changes in the relaxation times for motion of Ti ions measured with Quasi-elasticneutron-scattering (QENS). The current observations do not indicate that the paraelectric-ferroelectric phase transition in BaTiO 3 is primarily caused by an increase in the size of the microscopic polar clusters or critical slowing down of Ti ionic motion. The sharp and strong increases in peak widths and peak intensities during cooling through T C is explained as a result of microstrains that are developed at microdomain interfaces during paraelectric-ferroelectric phase transition.3

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We report our study on the emission response of a magnetic nanocontact with dynamic polarizer in perpendicular magnetic field. In this configuration three modes are accessible, two of which correspond to the precessional motion of a vortex in one of the two ferromagnetic layers with the other working as a static polarizer. At high currents a third mode can be observed that is ascribed to the simultaneous precession of two vortices, one in each layer, with the other layer working as a dynamic polarizer.

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