Adding 1_??_6% of Fe to the purest Al (99.999%), the effect of cooling velocities on the microstructure of cast Al-Fe alloys has been studied. As the result of retardation of the crystallization of FeAl
3, the eutectic point is supercooled if the alloys are cooled rapidly, and the apparent eutectic point shifts to the Fe-side. On the contrary, if the alloys are cooled slowly, the primary crystals of FeAl
3 segregate in the mother-liquor and sink to the bottom of the ingot. Utilising the phenomena of segregation of the primary crystals, the composition for the eutectic point of the Al-Fe system has been studied and assigned to be 1.7% Fe. Mechanical properties of the Al-Fe alloys, cooled at various rates, have also been measured.
Adding 1_??_10% Si to Al-Fe alloys, containing 5% of Fe, the molten alloys are cooled very slowly (10°/1 hr.) from the liquid in a Tammann-tube. Then structure of the ingot is examined as to the state of segregation of the primary crystals, the sorts of the ternary compounds and also the change of the phases during cooling. Further the composition of the mono-variant eutectic line, existing in the Al-Fe-Si system, has been determined by analysing the segregated portion of the ingots.
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