Tensile property and cold formability of a Mg96Zn2Y2 alloy sheet with a long-period ordered phase

Abstract

The tensile property and cold formability of a Mg96Zn2Y2 alloy sheet containing Mg-, long-period ordered (LPO)-, and Mg3Zn3Y2-phases were investigated. The Mg96Zn2Y2 alloy sheet exhibited a high yield stress of 320MPa and elongations of 11% at room temperature and could be prepared by hot-rolling. After, annealing at 773K for 0.6ks, although the yield stress decreased to 200MPa, elongation increased to 20%. Texture randomization due to re-crystallization of the Mg phase that occurred in the annealed Mg96Zn2Y2 alloy sheet was confirmed by EBSD analysis. The formability of a Mg96Zn2Y2 alloy sheet and an AZ31-O sheet was evaluated via a 90° V-bending test at room temperature. The annealed Mg96Zn2Y2 alloy sheet could be bent without cracking with a minimum bending radius per thickness of R/t=3.3, which is less than that of the as-rolled Mg96Zn2Y2 alloy sheet and the AZ31-O sheet. This improvement in the cold formability of the Mg96Zn2Y2 alloy sheet is considered due to an increase in randomness of the Mg phase that results from re-crystallization of the Mg phase.