Microgravity science and technology vol:10 issue:2 pages:95-105
During the EuroMIR 94 space flight two Al matrix composites with a different concentration of TiB2 and TiAl3 were melted, held during 50 min at the maximum temperature gradient and solidified in the CSK-1 tube furnace. On comparison with the ground processed reference samples it appears that the distribution of the particles in the molten zone is much more homogeneous. Also additional tests were performed in a gradient furnace (ASPF (Advanced Solidification Processing Facility) furnace), and an ordinary resistance furnace to complement the results of the space processed samples. A higher temperature gradient will give less convection and wizen the growth rate is below a critical velocity the particles will be pushed. These results are retrieved from the macro- and microstructure of the resolidified samples. Both the TiB2 and the TiAl3, particles settle, but the distribution differs. The small TiB2 particles form a network, as well inter- as intragranular, but the TiAl3 particles are randomly and individually distributed, mostly in the Al grains.