The effects of Ca and Mn on the microstructure, texture and mechanical properties of Mg-4 Zn alloy

Abstract

The microstructural evolution, texture and mechanical properties of nine Mg-4Zn-xCa-yMn alloys (x = 0.3, 0.6, 1.0; y = 0.2, 0.3, 0.7 wt.%) were investigated systematically. Alloying with Ca and Mn refined the grains of the extruded sheets and increased the unDRX fraction. Mn could be the heterogeneous nucleation site of Ca2Mg6Zn3 phase because of a good atom matching at the orientation relationship of (2¯1¯1¯)Mn//(12¯11)Ca2Mg6Zn3,〈2¯51¯〉Mn//〈1103〉Ca2Mg6Zn3. The traditional texture weakening effect of Ca was strongly decreased for the simultaneously addition of Mn. With increasing Ca and Mn concentration, the strength increased and ductility decreased. Mg-4Zn-0.6Ca-0.7Mn exhibited a good combination of ultimate tensile strength (320 MPa), yield strength (286 MPa) and elongation (16%). A model of strengthening indicated that grain boundary strengthening and precipitate strengthening made a large contribution to the strength of Mg-4Zn-0.6Ca-0.7Mn. In addition, the dynamic recrystallization, texture modification and the strengthening effect from different parts also have been analyzed in detail.

Keywords

• Mg–Zn–Ca–Mn alloy
• Texture
• Dynamic recrystallization
• Particle-stimulated nucleation
• Mechanical properties