Abstract
The microstructure of an Fe-40 at.% Al-0.5 at.% B-0.7 at.% C alloy in the as-extruded condition has been examined; in addition to the matrix B2 phase, four other phases were found to be present. These were Fe AlC with the 3 0.5 perovskite structure, Fe B, a tetragonal boride with the CuAl structure, 2 2 graphite (free carbon), and a new tetragonal phase that is probably coherent with the matrix. An orientation relationship exists between this tetragonal \\[ ] \\[ ] ) ) phase and the B2 matrix of the form 100 // 100 and (001 //(001 . From p m p m selected-area diffraction patterns, it is noted that this new tetragonal phase has lattice constants that can be related to the matrix lattice parameter a as a 4 a 0 p 0 and c a . Stacking-fault-like features are also present in the as-extruded p 0 material and these lie on the cube planes of the matrix. The new tetragonal phase precipitates frequently on the partial dislocations bounding these 'faults'; the precipitates themselves are rod shaped with a square cross-section. The axis of the rod coincides with the 100 directions in the matrix while the sides of the square cross-section lie along the matrix 110 directions. After annealing the extruded material, this new phase is no longer observed, leading to the conclusion that this phase is metastable.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.