Texture Evolution in Mg-Zn-Ca Alloy Sheets
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INTRODUCTION
IT is well known that Mg alloy sheets exhibit strong basal textures after thermomechanical treatment. Such a strong basal texture of Mg alloy sheets has an adverse effect on ductility and formability at room temperature. It has been demonstrated in several studies that the weakening of texture significantly improves the formability of Mg alloy sheets at room temperature.[1–4] Therefore, there have been numerous studies[5–16] on modifying the texture of Mg alloy sheets to a weaker and more random distribution of basal poles. It has been shown that the addition of rare earth (RE) elements such as Ce, Nd, and Y, for example, can significantly weaken and randomize the texture of Mg alloy sheets.[10–16] The texture of these alloy sheets is typically characterized by the broadening of angular distribution of basal poles along the transverse direction (TD). However, their peak positions vary among the alloys. Some alloy sheets show the splitting of the maximum basal pole intensity along the rolling direction (RD),[10–13] while others show it along the TD.[14–16] D.-W. KIM, B.-C. SUH, and M.-S. SHIM, Graduate Students, are with the Center for Advanced Aerospace Materials, Pohang University of Science and Technology (POSTECH), Pohang 790-784, South Korea, and also with the Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH). J.H. BAE, Senior Researcher, is with the Korea Institute of Materials Science, Changwon 641-831, South Korea. D.H. KIM, Professor, is with the Center for Non-crystalline Materials, Yonsei University, Seoul, South Korea. NACK J. KIM, Professor, is with the Center for Advanced Aerospace Materials, Pohang University of Science and Technology (POSTECH), and also with the Graduate Institute of Ferrous Technology, Pohang University of Science and Technology (POSTECH). Contact e-mail: [email protected] Manuscript submitted June 11, 2012. Article published online March 2, 2013 2950—VOLUME 44A, JULY 2013
Despite such a beneficial effect of RE elements on the modification of texture in warm- or hot-rolled Mg alloys, the high costs of these elements might prevent their widespread utilization as alloying elements for wrought Mg alloys. Therefore, it is necessary to find alternative alloying elements which have similar effects on texture evolution to those of RE elements. It has been recently shown that some of the Ca-containing alloys have weaker and more random textures[4,17,18] and better formability[4,19] than the ones without Ca addition. However, the detailed mechanisms responsible for such texture modifications by the addition of Ca are not clearly understood yet. In the present study, the effect of Ca addition on texture evolution and mechanical properties of Mg-Zn base alloys has been investigated.
II.
EXPERIMENTAL PROCEDURE
Alloys with nominal compositions of Mg-1Zn-1Ca (ZX11) and Mg-6Zn-1Ca (ZX61) in wt pct were prepared by induction melting using a steel crucible under Ar atmosphere. Analyzed compositions are Mg0.95Zn-0.9Ca and Mg-5.99Zn-0.98Ca
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