Optimizing Mechanical Properties and Thermal Stability of Age Hardenable Aluminum Alloys Through Theoretical Modeling, Alloy Modification and Thermal Mechanical Processing
Abstract
This proposal was to design and test an Al-Cu-Mg (Ag) alloy for moderate temperatures (up to 150 degrees C) application. A significant improvement in the creep resistance was primarily pursued in the program through enhancement of the yield strength and the thermal stability of the age-hardenable alloy. Major tasks have been finished as planned: 1) We identified the optimum structures of complex multiple secondary phase precipitates using dislocation slip simulation methods that we developed; focusing on Al-Cu-Mg based alloys with Cu: Mg ratios, vs. determined the omega phase as the main strengthening precipitate phase. 2) We constructed a special thermodynamic database (incorporating the metastable omega phase) to determine the absolute Cu and Mg concentration for optimum chemical driving forces of omega phase nucleation. 3) To control the formation (nucleation) of competing precipitate phases, we developed an effective and efficient approach to characterize effects of alloying elements. The computational tools, combining the state-of-the- art across-scale computational methods from first principles calculations to clustering strain analysis. We demonstrated how trace amounts of Mg and Ag additional catalyze omega phase nucleation and identified Si to be deleterious and that it must be eliminated. 4) We accordingly designed new alloys with compositions: Al -(4 to 5) Cu-(O.4 to 0.6) Mg-(O.4 to 0.06) Ag (wt%)with minimal Si content for the optimum strength and second phase thermal stabilities.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 30, 2005
- Accession Number
- ADA457228
Entities
People
- E. A. Starke
- G. J. Shiflet
Organizations
- University of Virginia