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

Uniaxial thermal compression tests at 1023 K were conducted on beta-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 slip dominated the plastic deformation in the strain scopes of 0.05-0.2. Basal slip coupled with 85 degrees <11 <(2)over bar> 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.

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In this paper, uniaxial thermal compression tests were conducted on beta-quenched Zr-4 alloy at 1023 K, with engineering strains ranging from 0.05 to 0.3. The microstructure evolution, deformation mode, and dynamic recrystallization (DRX) mechanism were systematically investigated using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) techniques. The results showed that prismatic slip dominated the plastic deformation in the strain scopes of 0.05-0.2, while basal slip coupled with tensile twins occurred in some residual undeformed grains when the strain reached 0.3. Evidence suggested the coexistence of discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX), and DRX associated with twins during the thermal compression. Distinctions were observed in the protruding nucleation mechanism of DDRX, where dislocations migrated and accumulated at the adjacent boundary instead of passing through it.