Superplastic micro deep drawability of nanocrystalline nickel sheet fabricated by electrodeposition

The nickel sheets with a thickness of 0.1mm were prepared by pulse electrodeposition process. To determine the optimum processing parameters relevant to micro deep drawing, uniaxial tensile tests were carried out at different temperatures and strain rates. Biaxial forming was subsequently performed. It is indicated that the micro deep drawability depends obviously on test temperature, and the chance of fracturing during micro deep drawing decreases with the increasing temperature. The nickel thin sheet can be readily drawn successfully using a hemispherical punch with diameter of 1mm at 723K and punch rates ranging from 0.1mm/min to 5mm/min. TEM and SEM were also used to examine microstructures of the as-deposited nickel sheet and deformed nickel specimens. After micro deep drawing most nickel grains grow to be micro scale. The deformation mechanisms of nanocrystalline nickel sheet during micro deep drawing be will be discussed herein.