力学性能优异的纳米结构镍.pdfVIP

ARTICLE IN PRESS Scripta Materialia xxx (2006) xxx–xxx Enhanced tensile ductility in an electrodeposited nanocrystalline Ni Changdong Gu, Jianshe Lian *, Zhonghao Jiang, Qing Jiang Key Lab of Automobile Materials, Ministry of Education, College of Materials Science and Engineering, Jilin University, Nanling Campus, Changchun, Jilin 130025, China Received 14 August 2005; received in revised form 1 2October 2005; accepted 21 October 2005 Abstract A fully dense nanocrystalline Ni exhibited high strength of about 1200 MPa and enhanced ductility of 7.5–8.3% at strain rates of 1.04 · 104–1.04 s1 and room temperature. The dislocation activity in the strain hardening stage and collective grains rotation after instability are suggested as being responsible for the enhanced ductility. 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords: Nanocrystalline; Mechanical properties; Microstructure; Nickel 1. Introduction strength, the embedded large grains stabilize the tensile deformation of the material [13,15]. Other evidence for Fully dense nanocrystalline (nc) materials are character- the importance of grain size distribution comes from the ized by high yield stresses and limited tensile ductilities [1– studies of the plastic deformations in ufc and nc Zn [16] 10]. The decrease of ductility with the decrease of average and ann