Phase transformation mechanisms involved in two-phase TiAl-based alloys. 1: Lamellar structure formation
- Office National d`Etudes et de Recherches Aerospatiales, Chatillon (France)
The present paper deals with the mechanism operating in one of the three major transformation modes appearing in two-phase TiAl-based alloys: the formation of the so-called {gamma}/{alpha}{sub 2} lamellar structure. This microstructure, the most typical of the alloys of this category, results from precipitation of {gamma}(L1{sub 0}) lamellae in the {alpha} (A3) or {alpha}{sub 2} (DO{sub 19}) matrix. This reaction is achieved through (1) pre-nucleation stage corresponding to the formation of a local f.c.c. type stacking sequence by the movement of Shockley partials; and (II) nucleation and growth stages involving both ordering and ledge movement. The presence of numerous order domain boundaries in a given lamellar precipitate is explained by the encounter of separately nucleated order domains.
- OSTI ID:
- 271715
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 1 Vol. 44; ISSN XZ504Y; ISSN 1359-6454
- Country of Publication:
- United States
- Language:
- English
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