Microstructure evolution and mechanical property of Mg-Gd-Y-Zn-Zr alloy wires prepared by hot drawing

Abstract

This study examined the effects of hot drawing deformation on the microstructure, texture, and mechanical properties of an Mg-9.5Gd-4Y–2Zn-0.3Zr alloy. A Φ6 mm extruded alloy bar was hot drawn down to a Φ1.2 mm wire through multi-passes. The results revealed that the intergranular 18R-long period stacking ordered (LPSO) phase was gradually changed into elongated shapes distributing along the drawing direction with increasing deformation strain, while the 14H-LPSO phase precipitates in the α-Mg matrix are progressively fragmented. The average grain size in the wire first increased from 4.6 μm to 25.9 μm and then decreased to 6.7 μm, and the volume fraction of dynamic recrystallisation first decreased from 95.5% to 8.6% and then increased to 48.7%. The initial weak //ED anomalous texture gradually changed and strengthened into a //DD dual basal texture. The Φ1.2 mm wire achieved a tensile strength of 553.5 MPa, a yield strength of 473.6 MPa, and an elongation of 2.5%. Calculations indicated that the high yield strength in Φ1.2 mm wire was mainly attributed to the high content of the large aspect ratio 18R-LPSO phase, high density of low angular grain boundaries, and strong basal texture.

Keywords

• Mg-Gd-Y-Zn-Zr alloy
• Hot drawing
• Recrystallisation
• Texture evolution
• Strengthening mechanism