UNDERCOOLING AND SUPERSATURATION OF ALLOYING ELEMENTS IN RAPIDLY SOLIDIFIED AL-8.5-PERCENT FE-1.2-PERCENT V-1.7-PERCENT SI ALLOY

Dispersion-strengthened Al-8.5% Fe-1.2% V-1.7% Si alloy was produced b y inert gas atomization and atomized melt deposition processes. Differ ential scanning calorimetry was used to estimate the extent of underco oling in the alloy powders as a function of powder size a nd in the at omized melt-deposited alloy as a function of process parameters. The e stimated undercooling was found to be a strong function of powder size and processing conditions and varied from 380-200 degrees C. Alloy po wders of diameter greater than 180 mu m did not experience any underco oling during solidification. X-ray diffraction analysis was performed to study the dependence of supersaturation of alloying elements and me tastable phase formation on the extent of undercooling. When the under cooled alloy was heated to about 400 degrees C, formation of Al-12(Fe, V)(3)Si phase with b cc crystal structure from the supersaturated mat rix was observed.