White beam imaging

Rupture of individual films in evolving liquid metal foams are investigated by means of highspeed X-ray radiography using white synchrotron light. At a frame rate of 5000 fps the rupture event is spread over 5 images. The images show that the remnants of the rupturing film are sucked into the surrounding Plateau borders in slightly less than 1ms which confirms well with a purely surface tension driven mechanism. A simple model and expresses the fact that the liquid in metal foams is very fluid and behaves like a conventional melt.

The flow of Al-Ge32 through a thin cavity was monitored by in-situ micro-radioscopy using white synchrotron radiation. X-ray images are recorded at 67 frames/s with a CMOS camera and an indirect X-ray detector. Liquid drainage and de- / reagglomeration of small aluminum-rich solid particle clusters – associated with the slurry's thixotropic behavior – are visualized. A map of the local displacement vectors of the liquid and the solid particles during injection of the slurry into the cavity is determined.

Figure 1: Series of 6 consecutive X-ray radioscopic images recorded with 5000 fps (Δt = 200 μs). They show the rupture of a cell wall and the rearrangement of neighbour ones in around 1 ms.

Figure 2: Radioscopic images taken at
(a) t = 1.155 s,
(b) t = 1.320 s and
(c) t = 1.455 s after starting the injection.
(d) Vector representation of particle and liquid motion calculated blockwise by sequential image cross-correlation (color indicates the motion amplitude).