The effect of molybdenum addition on properties of iron aluminides

The effect of the addition of up to 10 pct molybdenum on several metallurgical properties of Fe-28Al (at. pct) to which 1 pct TiB₂ was added for grain refinement has been studied. It was determined that the addition of molybdenum results in a decrease in grain size, an increase in the recrystallization temperature, and an increase in the DO₃ to B2 ordering transformation temperature. The solubility limit of molybdenum in the matrix of the base alloy was found to be about 6 pct. At this concentration, another 1 pct is dissolved in the TiB₂ precipitates. Tensile strengths were increased slightly by adding up to 2 pct Mo, but ductility decreased, even though grain sizes were reduced. The fracture mode in tension did not change with addition of molybdenum up to 2 pct.