NASA Langley Research Center has developed a functionally graded metal-metal composite structure. The structure is created using a method that avoids deleterious reactions between the different metal constituents, as would be observed via conventional melt processing. The results are unique alloy compositions and arrangements not typically available through conventional processing routes.
In order to improve the properties of monolithic metallic materials, alloying additions are made that create secondary phases and/or precipitate structures. These improvements must occur during melt solidification, and are governed by the thermodynamics of the process; that is, optimizing the metallic alloy is possible only as much as thermodynamics allow.
Developing novel methods to combine metallic compositions/alloys into a fully dense material is of interest to create materials with novel property combinations not available with monolithic alloys. While various approaches for layering two-dimensional materials exist, their capabilities are typically limited and non-isotropic. Further, while three-dimensional composites may be formed with conventional powder metallurgy processes, it is generally very difficult to control the arrangement of the phases; for example, due to randomness created by mixing powders.
This invention creates multiple alloy composite structures by forming a three-dimensional arrangement of a first alloy composition in which the three-dimensional arrangement has a substantially open and continuous porosity. The three-dimensional arrangement of the first alloy composition is infused with at least a second alloy composition. The three-dimensional arrangement is then consolidated into a fully dense solid structure.