Plastic Deformation of Electrodeposited Nanocrystalline Ni-W Alloys at High Temperatures

摘要

High-strength nanocrystalline Ni-W alloys containing 16.9 at. % W with average grain size of about 6 nm in diameter has been obtained by electrodeposition. At room temperature, the nominal tensile strength of the alloy was attained to about 1600 MPa, while the plastic strain before fracture was a very Sow value of 0.05 %. In this case, highly localized shear bands were observed near the fractured surface of the tensile test specimen. When the samples were annealed at 300℃ under a static tensile stress of 327 MPa, the plastic strain was largely increased at the initial period of annealing and then tended to saturate, i.e., 0.54 % for 2 h, respectively. Grain size of the Ni-W alloys was almost saturated to 10 ～ 15 nm after annealing at 300℃ for 2 h. It may be expected that the high tensile stress during grain growth might be effective to obtain the large uniform plastic deformation of nanocrystalline Ni-W alloys.