Improving Mechanical Properties of Mg-Zn-Nd-Zr Alloy by Low Alloying with Yb and Corresponding Strengthening Mechanisms

Abstract

This research was aim to develop a high-strength Mg alloy with low-alloying with the Yb element based on the Mg-6Zn-3Nd-0.5Zr alloy. The microstructure evolution and corresponding strengthening mechanisms of the Mg-6Zn-3Nd-0.5Zr-xYb were systemically investigated. The results indicated that the phase compositions were changer by the Yb addition. The Mg-Zn phases disappeared while a new phase, (Nd,Yb)Zn2, were formed. The volume fractions of the second phases increased with the increase of Yb content. And the volume fractions of the second phases of as-extruded alloys were slightly higher than that of the as-cast alloys due to the extra precipitation during the extrusion process. All as-extruded alloys exhibited a strong fiber texture with the (10[[EQUATION]]0) plane perpendicular to ED and the [[[EQUATION]]100] direction parallel to ED. The Yb addition improved the DRX degree, but has little effect on the grain orientation, and adjusted the texture intensities by influencing the DRX process. The Yb10 alloy exhibited the best mechanical properties, which should be attributed to the grain boundary strengthening and texture strengthening effects.

Keywords: Mg alloy, High strength, ZK60, Mg-Zn-Nd-Yb-Zr, Strengthening mechanisms