Mechanical characteristics under monotonic and cyclic simple shear of spark plasma sintered ultrafine-grained nickel

作者：Dirras G^*; Bouvier S; Gubicza J; Hasni B; Szilagyi T

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2009, 526(1-2): 201-210.

DOI：10.1016/j.msea.2009.07.034

• Nickel
• Powder consolidation
• Ultrafine-grained microstructure
• Simple shear test
• Twin grain boundary

The present work focuses on understanding the mechanical behavior of bulk ultrafine-grained nickel specimens processed by spark plasma sintering of high purity nickel nanopowder and subsequently deformed under large amplitude monotonic simple shear tests and strain-controlled cyclic simple shear tests at room temperature. During cyclic tests, the samples were deformed up to an accumulated von Mises strain of about epsilon(VM) = 0.75 (the flow stress was in the 650-700 MPa range), which is extremely high in comparison with the low tensile/compression ductility of this class of materials at quasi-static conditions. The underlying physical mechanisms were investigated by electron microscopy and X-ray diffraction profile analysis. Lattice dislocation-based plasticity leading to cell formation and dislocation interactions with twin boundaries contributed to the work-hardening of these materials. The large amount of plastic strain that has been reached during the shear tests highlights intrinsic mechanical characteristics of the ultrafine-grained nickel studied here.

• 出版日期2009-11-25