Title: Effect of Co addition on deformation-induced martensitic transformation in Cu-Zr alloy

Authors: Jeong-Soo Kim; Byung-Jin Kim; Woo-Chul Kim; Min-Young Na; Do-Hyang Kim; Won-Tae Kim

Addresses: Center for Noncrystalline Materials, Department of Materials Science & Engineering, Yonsei University, 134 Sinchon-dong, Seodaemun-gu, Seoul 120-749, South Korea ' Center for Noncrystalline Materials, Department of Materials Science & Engineering, Yonsei University, 134 Sinchon-dong, Seodaemun-gu, Seoul 120-749, South Korea ' Center for Noncrystalline Materials, Department of Materials Science & Engineering, Yonsei University, 134 Sinchon-dong, Seodaemun-gu, Seoul 120-749, South Korea ' Center for Noncrystalline Materials, Department of Materials Science & Engineering, Yonsei University, 134 Sinchon-dong, Seodaemun-gu, Seoul 120-749, South Korea ' Center for Noncrystalline Materials, Department of Materials Science & Engineering, Yonsei University, 134 Sinchon-dong, Seodaemun-gu, Seoul 120-749, South Korea ' Department of Optical Engineering, Cheongju University, 36 Naedok-dong, Sangdang-gu, Cheongju, Chungbuk 360-764, South Korea

Abstract: Thermal stability, phase transformation after deformation and mechanical properties of B2 phase alloy with the compositions of Cu_50-xCo_xZr₅₀ (x = 2, 4, 6, 10, 15, 20, 25, 30, 40, 45 and 50) have been investigated in the present study. The addition of Co in Cu₅₀Zr₅₀ alloy effectively improves the stability of B2 phase. The M_s and A_s temperatures generally decrease with increasing Co content. Before deformation, the alloys with x = 10, 15, 20, 25, 30, 40, 45 and 50 consist of B2 phase. After deformation, B2-B19´ martensitic transition occurs in x = 10, 15, 20 and 25 alloys, and B2-B33 martensitic transition occurs in x = 50 alloys. No martensitic transformation occurs in x = 40 and 45 alloys. The alloys with x = 10, 15, 20 and 25 exhibit double yielding phenomenon and higher strain-hardening rate, owing to B2-B19´ martensitic transformation during deformation. The alloys with x = 30, 40, 45 and 50 exhibit lower strain-hardening rate, in spite of conventional dislocation slip or B2-B33 martensitic transformation.

Keywords: copper; cu-zr alloys; zirconium; B2 phase; martensitic transformation; cobalt; thermal stability; phase transformation; deformation; mechanical properties; martensitic transition; metallic glasses; double yielding; strain hardening.

DOI: 10.1504/IJNT.2016.077078

International Journal of Nanotechnology, 2016 Vol.13 No.4/5/6, pp.278 - 287

Published online: 20 Jun 2016 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article