Abstract
The mechanism of formation of the fine duplex microstructure resulting from the α → γ transformation in water-quenched Ti-48Al-2Mn-2Nb alloys was studied using transmission and analytical electron microscopy. As-cast Ti-48Al-2Mn-2Nb alloys were heat treated in the a phase field and water quenched to room temperature. The resulting microstructure (referred to as a fine duplex microstructure) consisted of equiaxed grains and abutting lath colonies. Both the colonies and the grains were composed of the γ phase, twinned γ laths, and α2 laths. It was found that the transformation from α to γ in the fine duplex microstructure took place through long range diffusional processes, and competitive growth between the equiaxed and lath morphology occurred. Nucleation of the γ phase from the α matrix can occur through nucleation on stacking faults, followed by growth through the sympathetic nucleation and growth Qf new γ laths on a substrate lath. The observed misorientations and the interfacial structures between the laths were found to be consistent with such a mechanism. Competition between such nucleation and growth mechanisms for the equiaxed and lath morphologies of γ leads to the formation of lath colonies (of γ and α2) interspersed with equiaxed grains in these alloys.
| Original language | English |
|---|---|
| Pages (from-to) | 1661-1673 |
| Number of pages | 13 |
| Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
| Volume | 27 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - 1996 |
| Externally published | Yes |
ASJC Scopus Subject Areas
- Condensed Matter Physics
- Mechanics of Materials
- Metals and Alloys