| The characterization of boride such as morphology, distribution, crystal structure, and chemical composition was investigated using Ti-47Al-2Cr-4Nb alloy containing boron. The predominant boride morphology varied from a curved lacy type to a long fibrous needle (or plate) type and a blocky type consisting of bunches of hexagonal needles as the composition increases from 0.1 at.%B to 3.0 at.%B. The borides were different in distribution, chemical composition and crystal structure depending on their morphologies. The lacy boride at low B content appeared as the layered structure consisting of ordered β₂(B2), Ti₃B₄(D7_b), and TiB (B_f) Phase. The fibrous needle (or plate) type boride was determined to be TiB(B27) phase, whereas blocky boride was revealed to be TiB₂(C32) Phase well known in binary TiAl alloys containing B. |
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