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Titolo:
On the microstructural stability of TiAI/Ti3Al polysynthetically twinned crystals under creep conditions
Autore:
Wegmann, G; Maruyama, K;
Indirizzi:
Tohoku Univ, Grad Sch Engn, Dept Mat Sci, Sendai, Miyagi 9808579, Japan Tohoku Univ Sendai Miyagi Japan 9808579 ci, Sendai, Miyagi 9808579, Japan
Titolo Testata:
PHILOSOPHICAL MAGAZINE A-PHYSICS OF CONDENSED MATTER STRUCTURE DEFECTS ANDMECHANICAL PROPERTIES
fascicolo: 10, volume: 80, anno: 2000,
pagine: 2283 - 2298
SICI:
1364-2804(200010)80:10<2283:OTMSOT>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
LAMELLAR TIAL ALLOYS; AL ALLOYS; DEFORMATION; DEPENDENCE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
29
Recensione:
Indirizzi per estratti:
Indirizzo: Wegmann, G GKSS Res Ctr, Inst Mat Res, Max Planck Str, D-21502 Geesthacht,Germany GKSS Res Ctr Max Planck Str Geesthacht Germany D-21502 Germany
Citazione:
G. Wegmann e K. Maruyama, "On the microstructural stability of TiAI/Ti3Al polysynthetically twinned crystals under creep conditions", PHIL MAG A, 80(10), 2000, pp. 2283-2298

Abstract

The lamellar structure of polysynthetically twinned (PST) specimens has been characterized before and after creep testing in terms of a quantitative description of the microstructural variablest lamellar spacing, alpha(2) spacing and alpha(2) volume fraction. An apparent alpha(2)-->gamma phase transformation taking place when the samples were held at 1150K was encounterednot only in creep-deformed specimens but also in a simply heat-treated specimen. The transformation of the alpha(2) phase into the gamma phase took place by partial dissolution of alpha(2) lamellae, resulting in a substantial increase in the spacing of the alpha(2) lamellae. The driving force for the alpha(2) decomposition was identified as the chemical force to complete the thermodynamic equilibrium that was not reached in the as-grown PS? crystals. Two processes of lamellar refinement during creep deformation were identified, namely mechanical twinning parallel to the lamellar interfaces and secondary precipitation of gamma phase in alpha(2) lamellae. Mechanical twinning parallel to the lamellar interfaces was much more pronounced in soft-oriented PST specimens than in hard-oriented PST specimens. Both refinement processes led to an increase in the total number of interfaces even though some alpha(2)-gamma interfaces disappeared as a consequence of alpha(2) dissolution. Both refinement processes may contribute to the self-strengthening of lamellar alpha(2) + gamma alloys in the course of creep and hence the superior creep resistance of the lamellar microstructure.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/09/20 alle ore 16:15:08