Effect of Alloy Composition and Processing on the Structure and Properties of I/M Al-Li-X Alloys.

摘要

The major objectives of this program were to characterize the microstructure, deformation and fracture modes of Al-Li-X alloys with emphasis on determining the relationships between alloying elements, processing parameters, microstructure, and deformation and fracture behavior. We have found that the growth mechanism of T1 precipitate plates occurs by the diffusional glide of Shockley partials on (111) matrix planes and that the growth ledges migrate by the ledge-kink mechanism. Plastic deformation prior to aging was shown to decrease the T1 plate length and thickness, increase the number density by almost two orders of magnitude, increase the yield strength by 100 MPa while simultaneously reaching peak strength in 20% of the time required without plastic deformation. Keywords: Aluminum lithium alloys, Microstructure, Property relationships, Materials processing. (js)