Abstract
Unidirectional recrystallization in cold-swaged Ni was investigated over a temperature gradient range of 140∼900 K/cm. It was found that recrystallization structures depend strongly on the temperature gradient and transfer rate of the hot zone in addition to the cold-swaged reduction. Secondary recrystallized grains at high temperature gradients grew larger and loger with increased swaging reduction. Single crystals were found in the specimens cold-swaged by 81% under suitable conditions. These conditions were given by a curve drawn through the transfer rates of 0.55, 1.4 and 2.8 μm/s and the temperature gradients of 900, 660 and 450 K/cm respectively. Primary recrystallized region became narrower and the grain size just in front of the secondary recrystallization became smaller with increasing temperature gradient. At the temperature gradient of 900 K/cm the recrystallized structure consists of highly elongated grains aligned parallel to the transfer direction, that grew directly from the deformed region. The growth process was observed up to the rate of 27.8 μm/s.
