Orientation Effect in the Particle Stimulated Nucleation of Recrystallization

Abstract

The second phase particles present in commercial alloys have a strong influence on the recrystallization kinetics, microstructure and texture. By varying the alloying composition and material processing, the distribution of second phase particles can be changed, making it possible to control grain size and texture. It is known that there is lattice rotation around the particles after deformation, in a so-called particle deformation zone (PDZ), which is though to be important in randomizing the texture after recrystallization though particle stimulated nucleation (PSN). Although the basics of PSN are well accepted, the role of the local distribution of stored energy and its link to local lattice rotation is not well understood, making it impossible to successfully predict PSN efficiency. In this paper, we present a new method for studying the deformation around particles at using high-resolution digital image correlation (HRDIC) and electron backscatter diffraction EBSD. Combining the two techniques makes it possible, for the first time, to relate the local deformation fields to remnant changes in local lattice orientation. Initial measurements are made on a model Al-Si alloy deformed in compression to 50%. Our analysis shows that the material deforms heterogeneously with high levels of deformation localized along slip bands. EBSD analysis shows that the lattice distortion in these bands is minimal. The HRDIC analysis clearly shows particles interrupt the shear banding. Local lattice rotation measured by EBSD is considerably less than expected from the measured deformation.