Effect of Nd and Y on the microstructure and mechanical properties of ZK60 alloy

The effect of neodium (Nd) and yttrium (Y) on the microstructure and tensile properties of ZK60 alloy are investigated. Experimental results show that an addition of neodium and yttrium both brings about precipitation of a new Mg41Nd5 and Mg3Zn6Y (I) phases and refine the as-cast grains. After hot extrusion, the alloy added with Nd and the alloy with Nd and Y are greatly refined through dynamic recrystallization by means of the pining effect of particles or precipitates. As a result, very finer grains with size of 4-8 μm are obtained in the alloy with Nd and Y. However, the grain size of the alloy with Nd is relatively large. This suggested that the combination of Nd and Y addition has a great effect on grain refining during dynamic recrystallization, and leads to either the increase of both the melting temperatures of the eutectic phases and the melting temperature of the alloys or the increase of the yield strength and tensile strength of the alloy with Nd and Y at room temperature. In contrast, the elongation of both ZK60 and the alloy with Nd are higher than that of the alloy with Nd and Y.