Deformation of cube-textured aluminum studied using laser-induced photoelectron emission
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L.E. Levine Metallurgy Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8553 (Received 7 February 2007; accepted 8 May 2007)
The evolution of the kinetic energy distribution of photoelectrons from a cube-oriented aluminum sample during tensile deformation was probed with a retarding field energy analyzer. Because of the anisotropy of the aluminum work function, the electron-energy distribution is altered as the area fractions of the major surface planes change during deformation. In cube-textured aluminum, deformation reduces the {100} area fraction and the relatively low energy electrons from these surfaces. Conversely, the {110} and {111} area fractions and the relatively high energy electrons from these surfaces both increase. These changes are quantitatively consistent with texture analysis by electron backscattered diffraction (EBSD). They reflect deformation-induced production of {111} surfaces by slip and the exposure of {110} surfaces by grain rotation. Photoelectron kinetic energy measurements supplement EBSD measurements and are readily acquired in real-time.
I. INTRODUCTION
Aluminum has a face-centered-cubic (fcc) structure with lattice parameter a ⳱ 0.4041 nm. In general, the deformation of aluminum and its alloys is realized by twelve {111}〈110〉 slip systems1,2; in addition, slip on {100}, {110}, and {112} planes has been observed in aluminum at various temperatures.2–9 Deformation of single-crystal aluminum has been extensively studied to clarify the mechanisms of dislocation multiplication, lattice rotation, and cell structure formation.10–13 In polycrystalline aluminum, deformation can induce grain rotation. The formation of cell or subgrain structure and grain rotation control texture development in these materials and have considerable influence on their mechanical properties.12,14–18 Traditionally, bulk texture has been analyzed with xray and neutron diffraction.19,20 A recently developed technique, electron backscattered diffraction (EBSD), has been widely applied to quantitatively characterize local crystal orientation and misorientation between neighboring subgrains/grains.21,22 EBSD takes advana)
Address all correspondence to this author. Present address: Department of Engineering Technology, University of Houston, Houston, Texas 77204. e-mail: [email protected]. DOI: 10.1557/JMR.2007.0313 2582 J. Mater. Res., Vol. 22, No. 9, Sep 2007 http://journals.cambridge.org Downloaded: 23 Mar 2015
tage of the diffraction of high energy electrons when the sample is tilted about 70° normal to the incident beam. Under these conditions, diffraction from the first few nanometers atomic planes produces arrays of linear structures (Kikuchi patterns) that reflect the local crystal structure. Coherent patterns are produced only by electrons that have undergone a single scattering event. The failure of multiply scattered electrons to contribute to the observed patterns has been exploited to achieve effective spatial resolutions as low as 10–30 nm in aluminum and brass using f
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