Effects of composition and fabrication practice on resistance to annealing and creep of aluminum conductor alloys

Annealing characteristics and room temperature creep were evaluated for wire of aluminum conductor alloys Al-0.20 pct Fe (EC), Al-0.85 pct Fe and Al-0.75 pet Fe-0.15 pct Mg produced by both conventional rod fabrication and continuous rod fabrication. Throughout these studies changes in resistance to annealing and resistance to creep paralleled each other, suggesting a common mechanism for these phenomena. Increasing iron concentration from 0.20 to 0.85 pct greatly increased the number of iron-bearing intermetallic constituent particles and decreased resistance to annealing and creep. AddingMgto the high Fe alloy increased the resistance to annealing and creep. Samples from continuously fabricated rod of either EC or Al-Fe-Mg alloy had greater resistance to annealing and creep than that of conventionally fabricated samples. Transmission electron microscopic examinations revealed no precipitation of iron in the continuously fabricated rod indicating that elements in solution were retarding annealing and creep. Observations of strain aging support the hypothesis that segregation of elements to dislocations is probably the mechanism whereby creep and annealing were retarded. Formerly with Alcoa Laboratories, Alcoa Center, Pa.