High-pressure melt curve of shock-compressed tin measured using pyrometry and reflectance techniques
High-pressure melt curve of shock-compressed tin measured using pyrometry and reflectance techniques
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DOI：
10.1063/1.5132318
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发表时间：
2019-12
影响因子：
3.2
通讯作者：
B. L. La Lone;P. Asimow;O. V. Fat’yanov;R. Hixson;G. Stevens;W. Turley;L. Veeser
中科院分区：
文献类型：
--
作者：
B. L. La Lone;P. Asimow;O. V. Fat’yanov;R. Hixson;G. Stevens;W. Turley;L. Veeser
我们开发了一种测量受冲击金属样品熔化曲线的新技术，并利用它测量了10 - 30吉帕和1000 - 1800开尔文范围内锡的高压固 - 液相边界。使用单级粉末炮通过平板撞击对锡进行冲击压缩，我们在锡样品和氟化锂窗口的界面进行了精确的、时间分辨的辐射率、反射率和测速测量。通过这些测量，我们确定了界面处的温度和压力随时间的变化。然后我们将这些数据转换为温度 - 压力曲线，并将它们绘制在锡的相图上。锡样品最初被冲击进入高压固态γ相，随后源自撞击器背面的卸载波沿着等熵路径（卸载等熵线）降低界面处的压力。当卸载等熵线到达固 - 液相边界时，熔化开始，等熵线沿着相边界到低压。熔化的起始由温度 - 压力卸载等熵线斜率的显著变化来确定。在熔化开始之后，我们获得了连续且高度精确的熔化曲线测量。该技术允许通过一次辐射率和反射率实验沿着熔化曲线进行测量。将测量的温度数据与已发表的状态方程计算结果进行比较。我们的数据与一些已发表的熔化曲线计算结果吻合良好，但与并非所有的计算结果都吻合，这表明该技术具有足够的准确性来评估给定状态方程模型的有效性。
We have developed a new technique to measure the melt curve of a shocked metal sample and have used it to measure the high-pressure solid-liquid phase boundary of tin from 10 to 30 GPa and 1000 to 1800 K. Tin was shock compressed by plate impact using a single-stage powder gun, and we made accurate, time-resolved radiance, reflectance, and velocimetry measurements at the interface of the tin sample and a lithium fluoride window. From these measurements, we determined temperature and pressure at the interface vs time. We then converted these data to temperature vs pressure curves and plotted them on the tin phase diagram. The tin sample was initially shocked into the high-pressure solid γ phase, and a subsequent release wave originating from the back of the impactor lowered the pressure at the interface along a constant entropy path (release isentrope). When the release isentrope reaches the solid-liquid phase boundary, melt begins and the isentrope follows the phase boundary to low pressure. The onset of melt is identified by a significant change in the slope of the temperature-pressure release isentrope. Following the onset of melt, we obtain a continuous and highly accurate melt curve measurement. The technique allows a measurement along the melt curve with a single radiance and reflectance experiment. The measured temperature data are compared to the published equation of state calculations. Our data agree well with some but not all of the published melt curve calculations, demonstrating that this technique has sufficient accuracy to assess the validity of a given equation of state model.