Bimodal grained Mg-0.5Gd-xMn alloys with high strength and low-cost fabricated by low-temperature extrusion

Obtaining high strength in Mg alloys generally requires a high alloying content, especially rare earth ele-ments. However, as a lightweight alloy, the heavy rare-earth content has a negative impact on the density of Mg alloys and the related cost, which increases the exploration need of low rare-earth and low-cost Mg alloy. In this work, a new low-cost and high mechanical strength Mg-0.5Gd-xMn (x = 0, 0.5, 1.0, 1.5, 2.0 wt. %) alloys system was developed by the low-temperature extrusion at 250 degrees C. A typical bimodal grain structure was formed in as-extruded Mg-0.5Gd-xMn alloys. The results presented a gradually increased yield strength and ultimate tensile strength with the increment of the Mn content from 0 to 1.5 wt.%. The tensile yield strength and ultimate tensile strength reached 357 MPa and 364 MPa in Mg-0.5Gd-1.5Mn alloy, which was 62 MPa and 63 MPa higher than that of the Mg-0.5Gd alloy. The high performance was mainly due to the bimodal grain structure, which produced a good Hall-Petch strengthening and the back stress strengthening. The Mg-0.5Gd-xMn alloys possessed a feature of comparable high mechanical strength with heavy rare-earth content traditional Mg alloys but a much lower cost, which promotes the future application.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

A new low-cost and high mechanical strength Mg-0.5Gd-xMn (x = 0, 0.5, 1.0, 1.5, 2.0 wt. %) alloy system was developed by low-temperature extrusion. The alloy exhibited gradually increased yield strength and ultimate tensile strength with the increment of the Mn content. It possessed comparable high mechanical strength with heavy rare-earth content traditional Mg alloys but at a much lower cost.