This SGER award supports an investigation of combinatorial materials processing techniques for the synthesis of age-hardenable aluminum alloys by powder metallurgy, which can also be simultaneously strengthened by a dispersion of a finely divided oxide phase. It is well known that the sintering of aluminum powder is hampered by the presence of a tenacious oxide film on the surface, which interferes with pressing and sintering of the powder compacts. Beneficial effects of a dispersion of refractory oxide particles in an alloy matrix for enhanced hardness and strength are well known; however, the technical difficulties are not easily overcome without the use of complex methods. Mechanical alloying techniques have been known to provide a significant benefit for inducing solid-state diffusion and alloying of materials. Sintering processes, enhanced by methods of plasma activation and similar techniques, have been used in combination with mechanical alloying to synthesize refractory metals, intermetallics, metallic glasses and other difficult materials. This proposal deals with the study of a novel combination of mechanical alloying and chemically activated sintering of Al-Cu age-hardenable alloys. In this work, powders of aluminum will be mechanically alloyed with nanocrystalline powders of copper of platelet or flake morphology, and subjected to chemical activation by exposure to selected dilute organic acids, to provide suitable metal-organic surface films on the treated powders. The decomposition of these films at low temperatures will provide a highly activated surface for rapid sintering and densification of the alloyed powders. The sintered compacts will be heat treated to provide the age-hardening effect. At the same time, the dispersion of the aluminum oxide particles during mechanical alloying will provide the possibility of dispersion-strengthening of the sintered alloy. This project will provide unique and excellent opportunities to enterprising young engineering students to pursue cutting edge research in advanced materials and manufacturing techniques, and to learn about the potential benefits of nanostructured and engineered materials. The establishment of this research program will provide a unique opportunity for the PI to develop new and exciting classroom and laboratory instructional materials and courses to augment the research effort. The PI is participating in the George Washington Carver Project administered by the University of Arkansas, which provides promising and talented young undergraduate students from the historically black colleges and universities (HBCU) in the State of Arkansas an opportunity to experience the excitement and benefits of a science or engineering career. Under this program, selected youngsters will spend several weeks on campus, working with a faculty member and assisting in an on-going or specially developed research project. The PI will be supporting one undergraduate student under the Carver Project during the upcoming summer session. The student will work on this SGER project, assisting a graduate student in Mechanical Engineering, to set up and use the laboratory P/M processing equipment and conduct laboratory experiments. The student will learn research methods, laboratory procedures and safety issues, research documentation and analysis of experimental data, and acquire hands-on experience in the application of scientific and engineering principles in the development of advanced materials and manufacturing techniques.
