Stability of the two-phase (α/ω) microstructure of shocked zirconium

被引：33

作者：

Brown, D. W. ^{[1
]}

Almer, J. D. ^{[2
]}

Balogh, L. ^{[4
]}

Cerreta, E. K. ^{[1
]}

Clausen, B. ^{[1
]}

Escobedo-Diaz, J. P. ^{[1
]}

Sisneros, T. A. ^{[1
]}

Mosbrucker, P. L. ^{[3
]}

Tulk, E. F. ^{[3
]}

Vogel, S. C. ^{[1
]}

机构：

[1] Los Alamos Natl Lab, Los Alamos, NM 87545 USA

[2] Argonne Natl Lab, Argonne, IL 60439 USA

[3] Kinectrics Inc, Toronto, ON M8Z 5G5, Canada

[4] Queens Univ, Dept Mech & Mat Engn, Kingston, ON K7L 3N6, Canada

来源：

ACTA MATERIALIA | 2014年 / 67卷

关键词：

Diffraction; Zirconium; High pressure; Phase transformation; X-RAYS; PHASE-TRANSFORMATION; DISLOCATION MODEL; CRYSTALLITE-SIZE; LATTICE-STRAIN; PARTICLE-SIZE; OMEGA-PHASES; ALPHA-PHASES; DIFFRACTION; TITANIUM;

D O I：

10.1016/j.actamat.2013.12.002

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

The composite microstructure of two-phase (alpha/omega) shocked zirconium was studied in situ during heating (constant heating rate and isothermally) with high-energy X-ray diffraction techniques. The volume fraction of the metastable omega phase was monitored as the reverse phase transformation occurred: the start and finish temperatures being 470 and 550 K, respectively, during heating at 3 K min(-1). Moreover, isothermal transformation was observed when the shocked material was held at fixed temperatures from 420 to 525 K. Phase strains in each phase were monitored and separated in terms of thermal expansion and mechanical strains due to local phase constraints. Stresses in the alpha Zr were estimated to be a superposition of a hydrostatic component (of order -50 MPa) and uniaxial component (of order 600 MPa) along the c-axis. These stresses were relaxed during the reverse transformation. A high dislocation density was observed in both the a and omega phases in the as-shocked state. The dislocation density of the omega phase decreased preceding the reverse transformation, suggesting that it is the presence of the high concentration of defects in the omega phase which retarded the reverse transformation to the stable a phase and prevented the system from approaching equilibrium after the completion of the shock. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

引用

页码：383 / 394

页数：12

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