Microstructures and mechanical properties of extruded Mg–8Gd–0.4Zr alloys containing Zn

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2009-04, Vol.505 (1), p.13-19
• Main Authors: Liu, Ke, Zhang, Jinghuai, Rokhlin, L.L., Elkin, F.M., Tang, Dingxiang, Meng, Jian
• Format: Article
• Language: English
• Subjects: Age hardening; Magnesium alloys; Mg–Gd–Zn–Zr; Tensile strength
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2008.12.023

Microstructures and mechanical properties of the Mg–8Gd– xZn–0.4Zr ( x = 0, 1 and 3 wt.%) alloys in the as-cast, as-extruded and extruded-T5 conditions, have been investigated. The peak-aged Mg–8Gd–1Zn–0.4Zr alloy during isothermal ageing at 423 K acquires highest mechanical properties, with the highest ultimate tensile strength and yield tensile strength of 314 and 217 MPa, respectively. Addition of Zn has obvious effect on age hardening responses, especially for 1 wt.% Zn addition. It is due to a uniform distribution of β′ phase which can impede the movement of dislocations. However, addition of 3 wt.% Zn to the Mg–8Gd–0.4Zr alloy leads to a precipitation of Mg 3Zn 3Gd 2 phase (W-phase). This phase is incoherent with interface of the matrix and becomes cores of the fracture in tensile test at room or elevated temperature.