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Title: X-ray MicroBeam Characterization of the Near Surface Nanostructure Layer in Ti after Friction Stir Processing

Abstract

Plastic deformation and structural changes of a Ti surface after Friction Stir Processing (FSP) were analyzed by means of SEM, EBSD and advanced 3D polychromatic X-ray micro diffraction at the APS synchrotron. Spatially resolved 3D Laue diffraction allowed observing the changes in dislocation arrangement with depth in different regions of the FSP Ti. Formation of two specific zones was established: friction stir zone (FSZ), with an average thickness of 300 m, and thermal mechanical affected zone (TMAZ) with a thickness ofe of 800 m. It was shown that FSP generates a large number of dislocations. Maximal dislocation density is located within the TMAZ. Dislocation density gradually decreases and reaches the value typical for base metal. Within the TMAZ dislocations are distributed inhomogeneously. Inhomogeneity of plastic deformation and dislocations arrangement is found in 3D both within the individual grains and between separate grains.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shared Research Equipment Collaborative Research Center
Sponsoring Org.:
USDOE Office of Science (SC); USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
930789
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Reviews on Advanced Materials Science; Journal Volume: 15; Journal Issue: 1
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; TITANIUM; SURFACE PROPERTIES; NANOSTRUCTURES; DISLOCATIONS; FRICTION; DISTRIBUTION; nanostructure; x-ray diffraction; characterization; TEM

Citation Formats

Barabash, Rozaliya, Barabash, Oleg M, Ice, Gene E, David, Stan A, Feng, Zhili, and Horton Jr, Joe A. X-ray MicroBeam Characterization of the Near Surface Nanostructure Layer in Ti after Friction Stir Processing. United States: N. p., 2007. Web.
Barabash, Rozaliya, Barabash, Oleg M, Ice, Gene E, David, Stan A, Feng, Zhili, & Horton Jr, Joe A. X-ray MicroBeam Characterization of the Near Surface Nanostructure Layer in Ti after Friction Stir Processing. United States.
Barabash, Rozaliya, Barabash, Oleg M, Ice, Gene E, David, Stan A, Feng, Zhili, and Horton Jr, Joe A. Mon . "X-ray MicroBeam Characterization of the Near Surface Nanostructure Layer in Ti after Friction Stir Processing". United States. doi:.
@article{osti_930789,
title = {X-ray MicroBeam Characterization of the Near Surface Nanostructure Layer in Ti after Friction Stir Processing},
author = {Barabash, Rozaliya and Barabash, Oleg M and Ice, Gene E and David, Stan A and Feng, Zhili and Horton Jr, Joe A},
abstractNote = {Plastic deformation and structural changes of a Ti surface after Friction Stir Processing (FSP) were analyzed by means of SEM, EBSD and advanced 3D polychromatic X-ray micro diffraction at the APS synchrotron. Spatially resolved 3D Laue diffraction allowed observing the changes in dislocation arrangement with depth in different regions of the FSP Ti. Formation of two specific zones was established: friction stir zone (FSZ), with an average thickness of 300 m, and thermal mechanical affected zone (TMAZ) with a thickness ofe of 800 m. It was shown that FSP generates a large number of dislocations. Maximal dislocation density is located within the TMAZ. Dislocation density gradually decreases and reaches the value typical for base metal. Within the TMAZ dislocations are distributed inhomogeneously. Inhomogeneity of plastic deformation and dislocations arrangement is found in 3D both within the individual grains and between separate grains.},
doi = {},
journal = {Reviews on Advanced Materials Science},
number = 1,
volume = 15,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • A fine-grained Al–Mg/Al{sub 3}Ti nanocomposite was fabricated by friction stir processing (FSP) of an aluminum-magnesium (AA5052) alloy with pre-placed titanium powder in the stirred zone. Microstructural evolutions and formation of intermetallic phases were analyzed by optical and electron microscopic techniques across the thickness section of the processed sheets. The microstructure of the nanocomposite consisted of a fine-grained aluminum matrix (1.5 µm), un-reacted titanium particles (<40 µm) and reinforcement particles of Al{sub 3}Ti (<100 nm) and Mg{sub 2}Si (<100 nm). Detailed microstructural analysis indicated solid-state interfacial reactions between the aluminum matrix and micro-sized titanium particles to form Al{sub 3}Ti intermetallic phase.more » The hard inclusions were then fractured and re-distributed in the metal matrix by the severe thermo-mechanical conditions imposed by FSP. Evaluation of mechanical properties by hardness measurement and uniaxial tensile test determined significant enhancement in the mechanical strength (by 2.5 order of magnetite) with a high ductility (~22%). Based on a dislocation-based model analysis, it was suggested that the strength enhancement was governed by grain refinement and the presence of hard inclusions (4 vol%) in the metal matrix. Fractographic studies also showed a ductile-brittle fracture mode for the nanocomposite compared with fully ductile rupture of the annealed alloy as well as the FSPed specimen without pre-placing titanium particles. - Highlights: • FSP was employed to fabricate in situ nanocomposite. • The AA5052 Al alloy with pre-placed micro-sized Ti particles were utilized. • The structural analysis was revealed that the in situ formation of Al{sub 3}Ti nanophase. • The SZ grain structure was refined by PSN and ZHP mechanisms during DRX. • Hardness and tensile strength were improved up to ~2.5 times with a good ductility.« less
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