Materials Science and Engineering A 476 (2008) 46–59 Isothermal annealing of cold-rolled high-purity nickel H. Chang, I. Baker ∗ Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, United States Received 2 January 2007; accepted 18 April 2007 Abstract Electron backscattered patterns have been employed to reveal the details of the texture evolution in 90%, 95% and 97.5% cold-rolled, poly- crystalline, high-purity nickel specimens after 1 h anneals at a variety of temperatures. The results show that increasing the thickness reduction of cold-rolling both strengthened the cube texture developed after primary recrystallization, and increased its thermal stability at elevated temperatures. In the 90% cold-rolled specimens, secondary recrystallization occurred during annealing at 600 ◦ C but could not be completed at temperatures up to 1000 ◦ C. In contrast, extensive secondary recrystallization occurred in 95% and 97.5% cold-rolled specimens that were annealed at temperatures up to 1000 ◦ C. Most of the orientations of the second recrystallized grains were related to the primarily recrystallized cube texture by a 41 ◦ rotation around about 〈111〉 axis or a 27 ◦ rotation about 〈211〉, while a few secondary-recrystallized grains were found to have an 18 ◦ /〈100〉 misorientation relationship with the cube-oriented matrix. It appears that the preferred rotation angles/axes is dependent on the rolling reduction. © 2007 Elsevier B.V. All rights reserved. Keywords: Abnormal grain growth; Recrystallization; Texture; EBSP; Nickel 1. Introduction The cube texture formed by primary recrystallization in FCC metals and its evolution with annealing temperature have been the subject of considerable study [1–9]. In many studies, the cube texture was found to be strengthened or sharpened by increasing the annealing time or annealing temperature [1,10–17]. How- ever, in some cases, the primary recrystallized texture has been reported to be completely replaced by a quite different sec- ondary recrystallization texture upon further annealing. In a previous study on direction recrystallization of nickel [18,19], the primary-recrystallized cube texture was found to weaken at elevated temperatures until being completely replaced by a strong, single-component, secondary-recrystallization texture of {124} 〈21 ¯ 1〉. {124} 〈21 ¯ 1〉 is one of the best-known secondary recrys- tallization textures. It has been observed to form in rolled copper sheet by a 30–40 ◦ /〈111〉 rotation about the cube tex- ture [14]. Several other misorientation relationships between primarily recrystallized cube grains and the abnormally-grown grains have been reported, for example, 19 ◦ /〈100〉, 22 ◦ /〈111〉 and 38 ◦ /〈111〉 [10,20,21]. In sharp contrast, Abe and Yamada ∗ Corresponding author. Tel.: +1 603 646 2184; fax: +1 603 646 3856. E-mail address: ian.baker@dartmouth.edu (I. Baker). produced a cube texture by secondary recrystallization through isothermal annealing of 72.5% cold-rolled nickel, which had a nearly random primary recrystallization texture except for a weak cube texture component [22]. In the above studies, materials with different purities, differ- ent rolling conditions and different annealing conditions were used, all of which might contribute to the differences in the recrystallization behavior and the different orientations of the secondary recrystallized grains. This paper investigated the microstructure and texture evolution in 90%, 95% and 97.5% cold-rolled high-purity nickel after isothermal annealing at a variety of temperatures. The objective of this work is to reveal the recrystallization behavior of the high-purity nickel and under- stand how it can be affected by the degree of deformation. 2. Experimental methods A 12 mm diameter polycrystalline rod of 99.995 wt.% purity nickel was purchased from Alfa Aesar, with 24 ppm C, 34 ppm Fe and 2 ppm S as the major impurities. The as-received nickel rod was made by electron beam melting into ingot, forging and then cold swaging. The as-received nickel had a microstructure with grains that were elongated along the longitudinal direction of the rod due to the swaging, as shown in Fig. 1(a and b). The {100} pole figure of the nickel in its as-received state is shown in Fig. 1(c). Note that all the pole figures have the linear scale for 0921-5093/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2007.04.097