Abstract
Mg96Zn2Y2 alloys were subjected to equal channel angular pressing (ECAP) to systematically investigate changes in microstructure and tensile properties over eight passes. Mg96Zn2Y2 as-cast specimens consisted of three phases: α-Mg; LPSO (long period stacking ordered), and Mg3Zn3Y2. The phases proved stable against induced strain, enduring eight passes of ECAP, resulting in high-strain deformation. Deformation microstructure by ECAP can be divided into two regions: dynamically recrystallized (DRXed) α-Mg grain regions; and deformed regions including LPSO phase with kink deformation. The mean grain size of α-Mg grains decreased up to four passes of ECAP. However, the mean grain sizes in 4-pass and 8-pass specimens were 1.44 µm and 1.85 µm, indicating that mean grain size saturates due to dynamic recrystallization (DRX) after four ECAP passes. Basal texture of α-Mg grains inclined from tensile direction after one pass of ECAP; the intensity increased with increasing number of ECAP pass. LPSO texture also formed but with low intensity even after eight passes of ECAP. ECAP suppressed greatly DRX compared to extrusion under comparable strain. 0.2% proof stress increased up to four passes of ECAP and subsequently saturated due to DRX. On the other hand, elongation increased with increasing volume fraction of DRXed α–Mg region.
Fig. 11 Changes in (a) microstructure and (b) tensile properties as a function of equivalent strain induced by ECAP. Open symbols indicate data when extruded with R = 10.
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