An iterative approach to determine composition and heat treatment from the mechanical yield strength of an aluminum-lithium alloy

The development of a model to predict an alloy's microstructure and processing variables from specific mechanical properties or desired mechanical properties was the general emphasis of this investigation. The processing variables included the alloy's overall heat treatment, which involves the aging practice (time and temperature) and the solution heat treatment practice, and also the manufacturing processing of the alloy which involved direct extrusion processing. The particular mechanical property of interest for the aluminum-lithium demonstration alloy was the mechanical tensile strength. The microstructure was used as the basis for determining both the composition and the heat treatment processing requirements for obtaining the desired mechanical property. Specifically, a materials design model was designed to determine microstructural parameters from mechanical properties as the basis for prediction and/or specification of the heat treatment processing parameters. An iterative approach was taken to improve the initial determination of thermal processing and composition. The overall approach will design a precipitation hardened alloy heat treatment and composition to satisfy the design tensile strength and microstructure requirements of a given materials design and manufacturing program.