Evolution of Deformation and Recrystallization Textures in High-Purity Ni and the Ni-5 at. pct W Alloy
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INTRODUCTION
THE development of a strong cube texture (f001gh100i) in medium-to-high stacking fault energy face-centered cubic (fcc) materials, after heavy cold rolling and recrystallization, has received a lot of attention. The origin of cube texture is particularly interesting because, although a strong cube component is present in the recrystallization texture, no significant presence of the cube usually is found in the deformed state, as revealed from macroscopic pole figure or orientation distribution function (ODF) analyses. To resolve this apparent anomaly, two competing theories have been proposed, namely the oriented nucleation and the oriented growth theories.[1] The oriented nucleation theory maintains that cube grains will nucleate from the deformed state more frequently than grains of other orientations. Obviously, the cube grains will nucleate from the preexisting cube-oriented regions in the deformed matrix. In contrast, the oriented growth theory emphasizes that the origin of sharp cube texture lies in the selective growth of the nucleated cube grains. PINAKI P. BHATTACHARJEE, Assistant Professor, is with the Department of Materials Science and Engineering, Indian Institute of Technology Hyderabad, Ordinance Factory Estate, Yeddumailaram 502205, India. Contact e-mail: [email protected] RANJIT K. RAY, Visiting Scientist, is with the R&D Division, TATA Steel, Jamshedpur 831 001, India. NOBUHIRO TSUJI, Professor, is with the Department of Materials Science & Engineering, Graduate School of Engineering, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan. Manuscript submitted October 7, 2009. Article published online July 7, 2010 2856—VOLUME 41A, NOVEMBER 2010
The oriented growth theory is mainly based on the observations that certain misorientation relationships such as 40 deg around h111i can have a high mobility, and such a high mobility relationship is, in fact, found to hold well between the cube component and variants of the S-orientation (f123gh634i), which is one of the main components of deformation texture in many medium-tohigh stacking fault energy fcc materials. The origin of the preexisting cube-oriented regions and the reason for their preferential nucleation as maintained in the oriented nucleation model is not yet clear. It has been argued that the preexisting cube regions in the deformed matrix could originate by a rotational mechanism,[2] or they could be the remnants of the original cube-oriented grains existing in the hot-rolled materials.[3,4] The current work deals with the development of cube texture in high-purity Ni and Ni-5 at. pct W alloy prepared by powder metallurgy (PM) followed by heavy cold rolling and recrystallization. The understanding of the development of cube texture in these materials is critical for their intended use as a mechanically strong and textured substrate for coated superconductor applications according to the rolling assisted biaxially textured substrates method.[5] The substrate materials to be used for such applications should have a sh
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