Precipitation structures and mechanical properties of Al-Li-Zr alloy containing V

Abstract

It is known that Al-Li alloys possess high elastic modulus and low density, and the metastable [delta][prime] (Al[sub 3]Li) precipitate in these alloys affords considerable strengthening effect. However, with the strengthening resulting from the precipitation of [delta][prime] which is coherent with the matrix, these alloys suffer from low ductility and fracture toughness. It seems that the loss of ductility is the slip localization which occurs as a result of slip planes during deformation in connection with the specific hardening mechanism. As a result it indicates typical intergranular fracture. On the one hand, zirconium is used in many aluminum alloys to inhibit recrystallization during alloy processing. When zirconium is present in the alloy grain refinement occurs, which consequently, is considered as a factor that reduces the slip distance, and lowers the stress concentration across grain boundaries and at grain boundary triple points. Nevertheless, if only zirconium is added in Al-Li alloy it still shows intergranular fracture. By Zedaris et al., equilibrium phase Al[sub 3](Zr,V) in Al-Zr alloy containing V reduces the lattice mismatch along the c-axis with Al and, the L1[sub 2]-structure metastable precipitates Al[sub 3](Zr,V) in Al-Zr-V alloys are stable at elevated temperature. Therefore, it is interesting to elucidate themore » effect of V in Al-Li-Zr alloy at the precipitation structures and mechanical properties of these alloys.« less