05 a NCEM Brownian v1

Brownian Motion Observed in Metals: 

Brownian Motion Observed in Metals U. Dahmen, 05-6 Transmission electron microscope image of molten lead inclusions (dark) in solid aluminum matrix. At temperatures between the melting points of lead and aluminum, the small lead particles are observed to undergo rapid motion (the large particle on the right is too big to move). Scatter plot of the motion of a single Pb particle showing that its displacement from the origin, measured at 1/30 second intervals, is random, typical of Brownian motion. 5 nm The trajectories of individual inclusions can be followed on videotape and studied by applying the powerful image analysis capabilities of NCEM’s Image Analysis Facility. The motion of the particle charted here is the classic “random walk” predicted by the theory of Brownian motion. The temperature was 436˚C (between the melting points of Pb and Al), and 1056 individual frames were analyzed.