Dynamic reflectance changes in high-purity zirconium when it is shocked from the α to ω phase
| Autor: | B. M. La Lone, William Turley, J. M. Lang, L. R. Veeser, G. D. Stevens, R. J. Scharff |
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| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Phase boundary Phase transition Zirconium Materials science Analytical chemistry General Physics and Astronomy chemistry.chemical_element 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Omega Stress (mechanics) Wavelength chemistry Phase (matter) 0103 physical sciences 0210 nano-technology Tin |
| Zdroj: | Journal of Applied Physics. 124:185105 |
| ISSN: | 1089-7550 0021-8979 |
| Popis: | Flash lamp-illuminated integrating spheres have been used to measure the dynamic reflectance at the interface between a shocked metal target and a window maintaining the shock stress. In conjunction with radiance measurements, this method was recently used to study the pressure versus temperature phase boundary of the beta phase to body-centered-tetragonal transition of tin at around 13 GPa and, in separate experiments, to show a relationship between the reflectance and the phase fraction. We have used this technique to measure the ratio, R, of the dynamic reflectance relative to the ambient value for a high-purity zirconium sample attached to a sapphire window to study the alpha to omega phase transition. Nine experiments cover the range of stress, σ, from 4 to 16 GPa at six wavelengths from 500 to 1550 nm. The two phases in zirconium differ in volume by 6 GPa. Our results show that the relative reflectance decreases upon initial shock in the alpha state but increases as the material transforms to its omega state. The slope dR/dσ changes the sign around the phase transition. For shocks below 6 GPa, dR/dσ 0. In the stress region between 6 and 10 GPa, dR/dσ varies somewhat, perhaps due to the band structure or because the transition is incomplete there. |
| Databáze: | OpenAIRE |
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