Dynamic recrystallization and deformation model of β-quenched Zr-4 alloy subjected to elevated temperature compression

Abstract

Uniaxial thermal compression tests at 1023 K were conducted on β-quenched Zr-4 alloy to engineering strains of 0.05, 0.1, 0.2 and 0.3 in this paper. Electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) techniques were employed to systematically investigate the microstructure evolution, deformation mode and dynamic recrystallization (DRX) mechanism during the deformation. Schmid factor statistical results showed that prismatic <a> slip dominated the plastic deformation in the strain scopes of 0.05–0.2. Basal <a> slip coupled with 85° <11 2‾ 0> tensile twins occurring in some residual undeformed grains with their c-axis perpendicular to the compression direction jointly coordinate the deformation when the strain reached 0.3. Evidence suggested that discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX) and DRX associated with twins coexisted in the thermal compression. Although DDRX was accomplished through grain boundary protruding nucleation mechanism which was similar to previous reports, some distinctions were still experienced. In brief, dislocations migrated and accumulated at the adjacent boundary forming the protrusion inside the parent grain that produced dislocations instead of passing through the adjacent boundary.