Decomposition of the PO phase to the P63/mcm, hP18 structure in Nb-(24-36)Ti-40Al alloys

被引：16
作者：
Leonard, K. J. [2 ]
Tewari, R. [3 ]
Arya, A. [3 ]
Mishurda, J. C. [4 ]
Dey, G. K. [3 ]
Vasudevan, V. K. [1 ]
机构：
[1] Univ Cincinnati, Dept Chem & Mat Engn, Cincinnati, OH 45221 USA
[2] Oak Ridge Natl Lab, MST Div, Oak Ridge, TN 37831 USA
[3] Bhabha Atom Res Ctr, Div Mat Sci, Mumbai 400085, Maharashtra, India
[4] Aeronca Inc, Middletown, OH 45042 USA
来源：
ACTA MATERIALIA | 2009年 / 57卷 / 15期
基金：
美国国家科学基金会;
关键词：
Nb-Ti-Al alloys; Phase transformations; Phase stability; Omega phase; Transmission electron microscopy; AL; TRANSFORMATIONS; DEFORMATION;
D O I：
10.1016/j.actamat.2009.06.006
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
During the course of investigation of the phase equilibria in the Nb-Ti-Al system, decomposition of the ordered B2/beta(omicron) phase to an ordered omega-type product was observed in three Nb-(24-36)Ti-40Al (at.%) alloys following aging at 700 degrees C and on quenching from high-temperatures. Using transmission electron microscopy and X-ray diffraction techniques, this phase was determined as the hP18 variant of the P6(3)/mcm structure, with lattice parameters a(omicron) = 7.96 angstrom and c(omicron) = 5.57 angstrom, and an a(omicron) approximate to a(beta)root 6 and c(omicron) approximate to a(beta)root 3 relationship with the parent beta(omicron) phase. Ab initio calculations were carried out to estimate the energy of formation of various phases and to also establish the role of Nb in the stabilization of the hP18 phase. The results of the evolution and stability of this structure are presented and discussed. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
引用
收藏
页码：4440 / 4453
页数：14
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