Scandium in aluminum alloys
Release Date[2013-6-26 15:24:17]    Total access[544]Times

Aluminum alloys that contain dilute scandium additions display upgraded properties in several areas. In conjunction with zirconium, scandium forms very fine, coherent precipitates that impart strength and serve to inhibit recrystallization in aluminum alloys. In addition, these alloys display improved hot-cracking resistance during welding, and enhanced weld strength. Several scandium-aluminum alloys are currently under development, and some of the more interesting properties are presented in this article.

Effects of scandium

When added to aluminum, scandium is a potent dispersoid-strengthener, grain refiner, and recrystallization inhibitor. Scandium reduces hot cracking during welding, and provides the highest increment of strengthening per atomic percent of any alloying element when added to aluminum. The [Al.sub.3]Sc dispersoid is an [L1.sub.2]-type phase, which is coherent with the aluminum matrix. An extremely high coherency mismatch is observed for the [Al.sub.3]Sc phase, resulting in significant lattice strain, which serves to block dislocation motion and to impede grain growth. This mismatch is approximately 1.2%, compared with 0.8% for



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