Improvement of Mechanical Property Variation in Rapidly Solidified Al-Fe Alloy Hot Extruded Material for Electrical Conductors by Composition Gradient Control of the Billet

Hot extrusion materials produced by rapidly solidified Al-Fe alloy powder are a promising solution to replace copper-based electrical conductors because they exhibit good heat resistance and relatively high electrical conductivity. However, the in-situ temperature of the billet in extrusion dies tends to increase, which can affect the mechanical properties of the extruded material. The present work investigated the effect of the temperature change during hot extrusion on the mechanical property. Then the influence of the billet composition gradient control was studied. An air-jet atomized aluminum alloy powder containing a 2.3% iron by mass was pre-sintered into a cylindrical billet and then hot extruded. The in-situ temperature changed from a minimum of 656 K to a maximum of 700 K. The hardness of the extruded material varied from 66 HV to 54 HV when increasing the in-situ temperature. The grain size of the extruded material became coarse as the in-situ temperature increased, which caused the decrease in hardness. The billet's iron content was graded by mixing a different aluminum alloy powder containing 5% iron by mass to improve the hardness variation. As a result, the decrease in hardness of the extruded composition-graded material was suppressed. Fine Al-Fe intermetallic compounds increased due to the composition gradient, which can account for the improvement in the mechanical property variation.