Directly Imaging Fast Reaction Fronts

Kim, J S ; LaGrange, T B ; Reed, B W ; Campbell, G H ; Browning, N D

关键词: CHAIN REACTIONS;    DIFFRACTION;    ELECTRON MICROSCOPY;    ELECTRONS;    LASER;   

DOI  :  10.2172/902297
RP-ID  :  UCRL-TR-228301
PID  :  OSTI ID: 902297
Others  :  TRN: US200717%%526

美国|英语

来源: SciTech Connect

【 摘 要 】

Direct observation of fast intermetallic phase formation in Reactive Multilayer Foils (RMLFs) has been achieved. Snap-shots of the reaction appear to show development of mass-thickness contrast of the unmixed Al and Ni layers and an intermetallic phase. Electron imaging of these RMLF reaction fronts have never been attained in the past. The reaction front travels at {approx}10 meters per second as the nanoscale layers mix in an exothermic chain reaction, thus making traditional in situ electron microscopy {approx}10{sup 5} times too slow to produce such an image. The DTEM capability to produce several million electrons within nanoseconds for single-pulse imaging made this experiment possible. Additionally, the sample drive laser ensures reliable experiment initiation and repeatability. In no other way could such a high velocity event be captured at this magnification. RMLF reaction fronts continue to be analyzed via diffraction for complete phase evolution with respect to time. High quality diffraction patterns enable quantitative phase information to be obtained for future comparison to simulation.