UC San Diego

As pointed out by the in-depths studies on the mechanical and physical properties, intermetallic compounds have shown great potentials for applications in both structural and non-structural fields at elevated temperatures. [1] In spite of their high melting temperature, low density and excellent corrosion and oxidation resistance exhibited under extreme environments, unfortunately, many intermetallic materials are brittle at room temperature. Such brittleness in most cases limits the fabrication and processing for structural applications. [2] To eliminate or alleviate the influence of brittleness and further utilize intermetallics in industries, methods like alloying and coating, have been intensively studied on several typical intermetallics such as FeAl, Fe₃Al, and Ni₃Al. [3, 4] In the present study, the method of metal- intermetallic laminate composites synthesis [5, 6] was used as the approach to increase the overall ductility via combining constituent metals and intermetallics. Three systems were studied, including the binary nickel-aluminum reaction system, the ternary system on synthesis reactions between aluminum and nickel-chromium alloy, and the quaternary system using aluminum and nickel-iron-chromium alloy. A standard processing profile was used for complete reaction on all systems. To investigate the reaction evolution, the method of reaction interruption was used to study the microstructure evolution at different stages of the reactions in the systems. For Ni-Al system, MIL composites of Ni-(Al₃Ni₂+Al₃Ni) and Ni-Al₃Ni₂ were fabricated. For Ni-Fe-Al system, MIL composites synthesizing with Invar and aluminum, intermetallic phases of Al₇₉Fe₁₆Ni₆ and Al₈₄Fe₉Ni₇ were obtained. And for Ni-Cr -Fe-Al systems using Inconel and aluminum, intermetallic phases of Al₈₀Cr₃Fe₃Ni₇Mo and Al₈₅Cr₃Fe₃Ni₇Mo were found