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Title: Ordered omega derivatives in (Zr{sub 3}Al)-Nb alloys

Abstract

Various kinds of phase transformation, viz., spinodal decomposition, omega transformation, precipitation reactions and martensitic transformation can be induced in ternary (Zr{sub 3}Al)-Nb alloys in conditions far removed from equilibrium. Transformation sequences in alloys containing 3% niobium are described and rationalized in terms of some basic tendencies such as phase separation and chemical ordering in the {beta} (bcc) phase and displacive omega and {beta} to {alpha} (hcp) transformations. Microstructures of rapidly solidified alloy showed a distribution of cuboidal (D8{sub 8} phase) particles in the {beta} matrix. The periodic arrangement of these particles along the <100>{sub {beta}} directions was indicative of a spinodal transformation which preceded their formation. The {beta} {r_arrow} D8{sub 8} transformation could be accomplished by the superimposition of three processes, namely, chemical ordering, lattice collapse akin to {omega} transformation and vacancy ordering. During isothermal aging the D8{sub 8} phase transformed into the B8{sub 2} phase. The observed lattice correspondence and transformation morphology suggested that the D8{sub 8} to B8{sub 2} structural change involved the replacement of structural vacancies in the former by zirconium atoms without any reconstitution of the lattice. The evolution of the equilibrium Zr{sub 3}Al (L1{sub 2} structure) phase during prolonged aging were also studied.

Authors:
; ; ;  [1];  [2]
  1. Bhabha Atomic Research Center, Mumbai (India). Materials Science Div.
  2. National Inst. of Standards and Technology, Gaithersburg, MD (United States). Materials Science and Engineering Lab.
Publication Date:
OSTI Identifier:
323481
Report Number(s):
CONF-971201-
Journal ID: ISSN 0272-9172; TRN: 99:004263
Resource Type:
Conference
Resource Relation:
Conference: 1997 fall meeting of the Materials Research Society, Boston, MA (United States), 1-5 Dec 1997; Other Information: PBD: 1998; Related Information: Is Part Of Phase transformations and systems driven far from equilibrium; Ma, E. [ed.] [Louisiana State Univ., Baton Rouge, LA (United States)]; Atzmon, M. [ed.] [Univ. of Michigan, Ann Arbor, MI (United States)]; Bellon, P. [ed.] [Univ. of Illinois, Urbana, IL (United States)]; Trivedi, R. [ed.] [Ames Lab., IA (United States)]|[Iowa State Univ., Ames, IA (United States)]; PB: 703 p.; Materials Research Society symposium proceedings, Volume 481
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; PHASE STUDIES; ZIRCONIUM ALLOYS; ALUMINIUM ALLOYS; NIOBIUM ALLOYS; SOLIDIFICATION; AGING; CRYSTAL-PHASE TRANSFORMATIONS; MICROSTRUCTURE; ELECTRON MICROSCOPY; DATA

Citation Formats

Tewari, R, Dey, G K, Mukhopadhyay, P, Banerjee, S, and Bendersky, L A. Ordered omega derivatives in (Zr{sub 3}Al)-Nb alloys. United States: N. p., 1998. Web.
Tewari, R, Dey, G K, Mukhopadhyay, P, Banerjee, S, & Bendersky, L A. Ordered omega derivatives in (Zr{sub 3}Al)-Nb alloys. United States.
Tewari, R, Dey, G K, Mukhopadhyay, P, Banerjee, S, and Bendersky, L A. 1998. "Ordered omega derivatives in (Zr{sub 3}Al)-Nb alloys". United States.
@article{osti_323481,
title = {Ordered omega derivatives in (Zr{sub 3}Al)-Nb alloys},
author = {Tewari, R and Dey, G K and Mukhopadhyay, P and Banerjee, S and Bendersky, L A},
abstractNote = {Various kinds of phase transformation, viz., spinodal decomposition, omega transformation, precipitation reactions and martensitic transformation can be induced in ternary (Zr{sub 3}Al)-Nb alloys in conditions far removed from equilibrium. Transformation sequences in alloys containing 3% niobium are described and rationalized in terms of some basic tendencies such as phase separation and chemical ordering in the {beta} (bcc) phase and displacive omega and {beta} to {alpha} (hcp) transformations. Microstructures of rapidly solidified alloy showed a distribution of cuboidal (D8{sub 8} phase) particles in the {beta} matrix. The periodic arrangement of these particles along the <100>{sub {beta}} directions was indicative of a spinodal transformation which preceded their formation. The {beta} {r_arrow} D8{sub 8} transformation could be accomplished by the superimposition of three processes, namely, chemical ordering, lattice collapse akin to {omega} transformation and vacancy ordering. During isothermal aging the D8{sub 8} phase transformed into the B8{sub 2} phase. The observed lattice correspondence and transformation morphology suggested that the D8{sub 8} to B8{sub 2} structural change involved the replacement of structural vacancies in the former by zirconium atoms without any reconstitution of the lattice. The evolution of the equilibrium Zr{sub 3}Al (L1{sub 2} structure) phase during prolonged aging were also studied.},
doi = {},
url = {https://www.osti.gov/biblio/323481}, journal = {},
issn = {0272-9172},
number = ,
volume = ,
place = {United States},
year = {Thu Dec 31 00:00:00 EST 1998},
month = {Thu Dec 31 00:00:00 EST 1998}
}

Conference:
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