Structure of mechanically alloyed Ti-Al-Nb powders
- Univ. of Idaho, Moscow, ID (United States)
Ti-Al-Nb ternary powder mixtures containing 24Al-11Nb, 25Al-25Nb, 37.5 Al-12.5Nb, and 28.5Al-23.9Nb (at. pct) were mechanically alloyed in a SPEX 8000 mixer mill using a ball-to-powder weight ratio of 10:1. The structural evolution in these alloys was investigated by X-ray diffraction and transmission electron microscopy techniques. A solid solution of Al and Nb in TI was formed at an early stage of milling, followed by the B2/body-centered cubic (bcc) and amorphous phases at longer milling times. The stability of these phases and their transformation to other phases have been investigated by heat treating these powders at different temperatures. The B2/bcc phase transformed into an orthorhombic (O-Ti{sub 2}AlNb) or mixture of the orthorhombic (O) and hexagonal close-packed ({alpha}{sub 2}-Ti{sub 3}Al) phases, the proportion of phases being dependent on the powder composition. Milling beyond the amorphous phase formation resulted in the formation of an fcc phase in all the powders, which appears to be TiN, formed as a result of contamination of the powder.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC07-76ID01570
- OSTI ID:
- 78407
- Journal Information:
- Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 6 Vol. 26; ISSN 0360-2133; ISSN MTTABN
- Country of Publication:
- United States
- Language:
- English
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