Effects of Alloying Additions of Titanium, Molybdenum, Silicon, Hafnium and Tantalum on the Microstructure of Iron Aluminides near Fe3 Al

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Department of Materials Science and Engineering


Additions of titanium, molybdenum, silicon, hafnium and/or tantalum to FeAl alloys near the composition Fe3Al have been found to affect many microstructural features including antiphase domain size, types and crystallography of antiphase and interphase boundaries, and slip vectors. In addition, different microstructures are developed with changes in aluminum content in complex alloys containing molybdenum, titanium and hafnium. In particular, with decreasing aluminum level, the microstructure changes from a single phase D03 superlattice to a structure having elongated ordered domains with a thin layer of the disordered phase along the antiphase boundaries, and finally to a two-phase modulated structure with D03 domains aligned along 〈100〉 directions in a disordered matrix. Stabilization of the D03 structure through alloying with molybdenum and titanium causes the slip vector to change from the usually observed 〈111〉 to 〈110〉 which is in agreement with the crystallographic symmetry.

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© 1987

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Materials Science and Engineering