The deformation and fracture behavior of an electrodeposited nanocrystalline Ni under compression

A bulk and dense nanocrystalline Ni with an average grain size of 19 nm and a thickness of 5.4 mm was fabricated by an electro-deposition technique. The nc Ni had a preferable (2 0 0) growth texture along the depositing direction. Under compression test, the nc Ni exhibited a high strength of 2920 MPa and an accepted good ductility of 16%. A novel fracture character, i.e., the triple-junction shaped micro-cracks with the size varying from few to several tens of micrometers which run through the holistic fracture body of the nc Ni, was observed. The reason for the formation of such cracks is attributed to GB activities, which leads to the formation of nano-sized void, and the subsequent formation of micro-crack.

► A bulk nanocrystalline Ni with a thickness of about 5.4 mm is made. ► The nc Ni holds an ultrahigh strength of 2920 MPa and an accepted ductility of 16%. ► The deformation-induced grain growth and triple-junction cracks are observed.