Surface Specularity as an Indicator of Shock-Induced Solid-Liquid Phase Transitions in Tin.

Stevens, G. D. ; Lutz, S. S. ; Marshall, B. R. ; Turley, W. D.

Technical Information Center Oak Ridge Tennessee

关键词: Tin;    Phase transformations;    Melting;    Liquid-solid interfaces;    Shock waves;   

RP-ID  :  DE2008926661

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

When highly polished metal surfaces melt upon release after shock loading, they exhibit features that suggest significant surface changes accompany the phase transition. The reflection of light from such surfaces changes from specular (pre-shock) to diffuse upon melting. Typical of this phenonmenon is the loss of signal light in velocity interferometer system for any reflector (VISAR) measurements, which usually occurs at pressures high enough to melt the free surface. Unlike many other potential material phase-sensitive diagnostics (e.g., reflectometery, conductivity), that show relatively small (1%10%) changes, the specularity of reflection provides a more sensitive and definitive (>10x) indication of the solid-liquid phase transition. Data will be presented that support the hypothesis that specularity changes indicate melt in a way that can be measured easily and unambiguously.