Tensile Properties of Bulk Nanocrystalline Ni and Ni-W Fabricated by Sulfamate Bath

Abstract

Nanocrystalline materials with high strength have been reported in large numbers. In particular, there has been considerable research on electrodeposited nanocrystalline Ni (nc-Ni) and nc-Ni alloys. However, reported data vary widely especially in ductility. Therefore, it is necessary to obtain the true characteristic value of nc-Ni and nc-Ni alloys. In the present study, nc-Ni and nc-Ni-W was electrodeposited under different conditions in order to obtained bulk nc-Ni and nc-Ni-W with high tensile strength and good ductility. At first, bulk nc-Ni-W was fabricated using a sulfamate bath. Although the resulting bulk nc-Ni-W had inhomogeneous grain size and W-concentration, this sample exhibited plastic deformation behavior. Then, nc-Ni was fabiricated by four types of sulfamate baths. As a result, the nc-Ni obtained from a sulfamate bath containg added saccharine and 2-butyne-1,4-diol exhibited brittle behavior. In contrast, bulk nc-Ni obtained from sulfamate bath with a grain size of about 60 nm exhibited a tensile strength of about 1000 MPa and ductility of 8.8 %.