Enhancement of Corrosion Resistance and Mechanical Properties of Light-Weight Metals Through the Use of Graded Nonequilibrium Microstructures.
Annual rept. no. 2, 1 Nov 94-1 Dec 95,
PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF ENGINEERING SCIENCE AND MECHA NICS
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Designs for the future will place extreme demands on light-weight materials. In order to meet these future challenges, it is vital that an emphasis be placed on tailor-making materials with enhanced specific properties. Through the use of rapid solidification processing, advances have been made in our ability to engineer materials -- but we have yet to be able to tailor-make a light-weight alloy with all of the characteristics we desire. A new approach to tailor-making alloys with the enhanced properties we desire is to use nonequilibrium alloying techniques such as sputter or electron-beam e-beam evaporation to grade the structure and composition of an alloy during processing. Such alloys could be designed to take advantage of recent advances in enhancing both the mechanical properties and the corrosion resistance of Al and Mg. For conventional Al alloys, a combination of high-strength and superior localized corrosion resistance are mutually exclusive. In order to achieve high strengths, precipitates are necessary in the microstructure. On the other hand, in order to exhibit superior corrosion performance, a one phase structure is usually required precipitates can establish microgalvanic cells which lead to accelerated corrosion of the precipitate or the alloy adjacent to the precipitate. However, both high-strength and superior corrosion resistance could be combined in one material if the structure and composition of the alloy were graded during nonequilibrium processing. Work during the second year of this investigation focused the production of e-beam evaporated nonequilibrium Al-Mo alloys at Idaho National Engineering Lab, the fabrication of an electron-beam e-beam evaporation system at Penn State, and an investigation of the influence of deposit morphology on alloy corrosion performance. MM
- Properties of Metals and Alloys