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Author: Zhang, H. × Subject: crystallization ×

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    Amorphous martensite in β-Ti alloys
    (London : Nature Publishing Group, 2018) Zhang, L.; Zhang, H.; Ren, X.; Eckert, J.; Wang, Y.; Zhu, Z.; Gemming, T.; Pauly, S.
    Martensitic transformations originate from a rigidity instability, which causes a crystal to change its lattice in a displacive manner. Here, we report that the martensitic transformation on cooling in Ti-Zr-Cu-Fe alloys yields an amorphous phase instead. Metastable β-Ti partially transforms into an intragranular amorphous phase due to local lattice shear and distortion. The lenticular amorphous plates, which very much resemble α′/α″ martensite in conventional Ti alloys, have a well-defined orientation relationship with the surrounding β-Ti crystal. The present solid-state amorphization process is reversible, largely cooling rate independent and constitutes a rare case of congruent inverse melting. The observed combination of elastic softening and local lattice shear, thus, is the unifying mechanism underlying both martensitic transformations and catastrophic (inverse) melting. Not only do we reveal an alternative mechanism for solid-state amorphization but also establish an explicit experimental link between martensitic transformations and catastrophic melting.
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    Generation of crystal-structure transverse patterns via a self-frequency-doubling laser
    (London : Nature Publishing Group, 2013) Yu, H.; Zhang, H.; Wang, Y.; Wang, Z.; Wang, J.; Petrov, V.
    Two-dimensional (2D) visible crystal-structure patterns analogous to the quantum harmonic oscillator (QHO) have been experimentally observed in the near- and far-fields of a self-frequency-doubling (SFD) microchip laser. Different with the fundamental modes, the localization of the SFD light is changed with the propagation. Calculation based on Hermite-Gaussian (HG) functions and second harmonic generation theory reproduces well the patterns both in the near- and far-field which correspond to the intensity distribution in coordinate and momentum spaces, respectively. Considering the analogy of wave functions of the transverse HG mode and 2D harmonic oscillator, we propose that the simple monolithic SFD lasers can be used for developing of new materials and devices and testing 2D quantum mechanical theories.