The influence of element Y on the mechanical properties of the as-extruded Mg-Zn-Y-Zr alloys

This work mainly investigated the mechanical properties of the as-extruded Mg-Zn-Y-Zr Mg alloys with different Y contents. It showed that when Zn content was constant (5.65 wt.%), the alloys with Y content from 1.17 to 1.72 wt.% could have the highest strength. XRD analysis and the tensile testing results showed that the alloys with Y content in the range of 0 to 1.72 wt.% were composed of alpha-Mg matrix and icosahedral quasicrystal I-phase, and with the quantity of I-phase increasing, the strength of the alloys was improved. When Y content varied from 1.72 to 3.69 wt.%, w-phase would be detected. Through comparing with the mechanical properties of the alloys, it could be found that the occurrence of w-phase will degrade the strength of the alloys. Based on the Zn (wt.%)/Y (wt.%) ratios of I-phase and w-phase and compared with different Zn (wt.%)/Y (wt.%) ratios of the alloys, the occurrence of w-phase have been explained. Fracture observations revealed that with Y content increasing, the quantity of Mg-Zn-Y phase distributed on the fracture surfaces would gradually increase. (c) 2006 Elsevier B.V. All rights reserved.