Evolution of Deformation and Recrystallization Textures in High-Purity Ni and the Ni-5 at. pct W Alloy

摘要

An attempt has been made to study the evolution of texture in high-purity Ni and Ni-5 at. pctW alloy prepared by the powder metallurgy route followed by heavy cold rolling (～95 pct deformation) and recrystallization. The deformation textures of the two materials are of typical pure metal or Cu-type texture. Cube-oriented ({001}<100>) regions are present in the deformed state as long thin bands, elongated in the rolling direction (RD). These bands are characterized by a high orientation gradient inside, which is a result of the rotation of the cube-oriented cells around the RD toward the RD-rotated cube ({013}<100>). Low-temperature annealing produces a weak cube texture along with the {013}<100> component, with the latter being much stronger in high-purity Ni than in the Ni-W alloy. At higher temperatures, the cube texture is strengthened considerably in the Ni-W alloy; however, the cube volume fraction in high-purity Ni is significantly lower because of the retention of the {013}<100> component. The difference in the relative strengths of the cube, and the {013}<100> components in the two materials is evident from the beginning of recrystallization in which more {013}<100>-oriented grains than near cube grains form in high-purity Ni. The preferential nucleation of the near cube and the {013}<100> grains in these materials seems to be a result of the high orientation gradients associated with the cube bands that offer a favorable environment for early nucleation.