DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Coupled strain-induced alpha to omega phase transformation and plastic flow in zirconium under high pressure torsion in a rotational diamond anvil cell

Journal Article · · Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing
ORCiD logo [1];  [2];  [3]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Ames Lab. and Iowa State Univ., Ames, IA (United States)
  3. Iowa State Univ., Ames, IA (United States)

Strain-induced α → ω phase transformation (PT) in the zirconium (Zr) sample under compression and plastic shear in a rotational diamond anvil cell (RDAC) is investigated using the finite element method (FEM). The fields of the volume fraction of the ω phase, all components of the stress tensor, and plastic strain are presented. Before torsion, PT barely occurs. During torsion under a fixed applied force, PT initiates at the center of the sample, where the pressure first reaches the minimum pressure for strain-induced α → ω PT, pdε, and propagates from the center to the periphery and from the symmetry plane to the contact surface. Salient increase of the shear friction stress and pressure at the center of a sample, so-called pressure self-multiplication effect observed experimentally for some other materials, is predicted here for Zr. It is caused by much higher yield strength of the phase in comparison with the phase. Except at the very center of a sample, the total contact friction stress is equal to the yield strength in shear of the mixture of phases and the plastic sliding occurs there. Due to the reduction in sample thickness and radial material flow during torsion, the ω phase can be observed in the region where pressure is lower than pdε, which may lead to misinterpretation of the experimental data for pdε. For the same applied force, torsion drastically promotes PT in comparison with the compression without torsion. However, the PT process in RDAC is far from optimal: (a) due to the pressure self-multiplication effect, the pressure in the transformed region is much higher than that required for PT; (b) the region in which PT occurs is limited by the pressure pdε and cannot be expanded by increasing a shear under a fixed force; and (c) the significant reduction in thickness during torsion reduces the total mass of the high-pressure phase. These drawbacks can be overcome by placing a sample within a strong gasket with an optimized geometry. It is shown that, due to strong pressure heterogeneity, characterization of α → ω and α → β PTs based on the averaged pressure contains large errors. Furthermore, the obtained results, in addition to providing an improved understanding of the strain-induced PTs, may be beneficial for the optimum design of experiments and the extraction of material parameters, as well as optimization and control of PTs by varying the geometry and loading conditions.

Research Organization:
Los Alamos National Laboratory (LANL)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC52-06NA25396
OSTI ID:
1458964
Alternate ID(s):
OSTI ID: 22829440
Report Number(s):
LA-UR-18-23858; {"Journal ID: ISSN 0921-5093",""}
Journal Information:
Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing, Journal Name: Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing Journal Issue: C Vol. 731; ISSN 0921-5093
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

References (39)

High-pressure mechanochemistry: Conceptual multiscale theory and interpretation of experiments journal November 2004
Omega phase in materials journal January 1982
New high-pressure phase transition in zirconium metal journal January 1990
Influence of the high pressure torsion die geometry on the allotropic phase transformations in pure Zr journal June 2010
First-principles study on the lonsdaleite phases of C, Si and Ge journal March 2003
Melting and Polymorphism at High Pressures in Some Group IV Elements and III-V Compounds with the Diamond/Zincblende Structure journal April 1963
Numerical study of stress and plastic strain evolution under compression and shear of a sample in a rotational anvil cell journal December 2010
Phase Transformations Under High Pressure and Large Plastic Deformations: Multiscale Theory and Interpretation of Experiments book January 2018
Is C60 fullerite harder than diamond? journal May 1994
Modeling and simulation of strain-induced phase transformations under compression and torsion in a rotational diamond anvil cell journal November 2010
Effect of Nb additions on the microstructure, thermal stability and mechanical behavior of high pressure Zr phases under ambient conditions journal April 2011
High-density amorphous phase of silicon carbide obtained under large plastic shear and high pressure journal February 2012
Strain-induced disorder, phase transformations, and transformation-induced plasticity in hexagonal boron nitride under compression and shear in a rotational diamond anvil cell: In situ x-ray diffraction study and modeling journal July 2006
Strain-induced phase transformation under compression in a diamond anvil cell: Simulations of a sample and gasket journal April 2014
X-ray Imaging of Stress and Strain of Diamond, Iron, and Tungsten at Megabar Pressures journal May 1997
A review on high-pressure torsion (HPT) from 1935 to 1988 journal January 2016
Phase transformations in nanograin materials under high pressure and plastic shear: nanoscale mechanisms journal January 2014
Shear-induced phase transition of nanocrystalline hexagonal boron nitride to wurtzitic structure at room temperature and lower pressure journal November 2012
Stress dependence of the mechanism of the olivine–spinel transformation journal April 1989
Nanoscale mechanisms for high-pressure mechanochemistry: a phase field study journal March 2018
Allotropic phase transformation of pure zirconium by high-pressure torsion journal October 2009
Phase changes and the equation of state of Zr journal August 2005
Localized polymorphic phase transformations in high-pressure faults and applications to the physical mechanism of deep earthquakes journal December 1987
First Experimental Observation of Shear Induced hcp to bcc Transformation in Pure Zr journal April 2009
Orientation dependency of the alpha to omega plus beta transformation in commercially pure zirconium by high-pressure torsion journal August 2011
FEM simulation of large deformation of copper in the quasi-constrain high-pressure-torsion setup journal September 2017
Plastic flows and strain-induced alpha to omega phase transformation in zirconium during compression in a diamond anvil cell: Finite element simulations journal January 2017
Effect of shear strain on the α–ε phase transition of iron: a new approach in the rotational diamond anvil cell journal June 2006
Low-pressure phase transformation from rhombohedral to cubic BN: Experiment and theory journal February 2002
First-principles calculations of phase transition, elastic modulus, and superconductivity under pressure for zirconium journal March 2011
Plastic flows and phase transformations in materials under compression in diamond anvil cell: Effect of contact sliding journal July 2013
Strain-induced phase transformations under compression, unloading, and reloading in a diamond anvil cell journal May 2013
Coupled phase transformations and plastic flows under torsion at high pressure in rotational diamond anvil cell: Effect of contact sliding journal December 2013
Shear-promoted phase transitions in Fe2SiO4and Mg2SiO4and the mechanism of deep earthquakes journal November 1993
Modeling and simulation of strain-induced phase transformations under compression in a diamond anvil cell journal November 2010
Enhancement of yield strength in zirconium metal through high-pressure induced structural phase transition journal November 2007
Effects of gasket on coupled plastic flow and strain-induced phase transformations under high pressure and large torsion in a rotational diamond anvil cell journal January 2016
Strain-induced phase transformations under high pressure and large shear in a rotational diamond anvil cell: Simulation of loading, unloading, and reloading journal March 2014
Crystal Structures of Titanium, Zirconium, and Hafnium at High Pressures journal April 1963

Cited By (1)