Scanning electron microscopic determination of the particle size distribution of an agglomerating phase in a metallic melt

The size distribution of TiB2 particles in an AlTi5Bl alloy and the coarsening owing to thermic interactions of the particles are examined. It is assumed that the particles grow by absorption of molecules, coalescence and agglomeration. A coagulation rate describes the collision frequency in dependence on the particle size. A statistical model of the collision processes leads to a log-normal distribution for the particle diameters. The truncation of the experimental size distribution owing to the finite resolution of the scanning electron microscope is included by an insert function. A fit of the measured section of the size distribution to a log-normal distribution provides the characteristic values (median and standard deviation) of the TiB2 particle distribution after different treatments of the melt.