Composition Optimization And Preparation Of High-strength,heat-resistant And Highly Conductive Aluminum Alloy Wires

In recent years,with the rapid development of domestic economy,so that the electricity load has increased sharply,and large capacity,high voltage,long-distance overhead transmission lines are being built,which requires a higher transmission capacity to reduce transmission losses,and the transmission capacity and transmission efficiency of the wire and its strength,electrical conductivity and heat resistance and other comprehensive performance is closely related.In this paper,a series of Al-ZrRE alloys were prepared by microalloying elements such as La,Ce,and Sc as a system,and the strength and electrical conductivity of the alloys were further improved by heat treatment processes.The effects of trace rare earth elements on the microstructure,mechanical properties,electrical conductivity and heat resistance of Al-Zr alloys were investigated by using OM,SEM,EBSD,eddy-current conductivity meter and electronic universal testing machine,and the optimal heat treatment process was explored to prepare a high-strength,heat-resistant and highly conductive aluminum alloy wire with a good match of strength and electrical conductivity.The main findings of this paper are as follows:Comparing the electrical conductivity and mechanical properties of Al-x Zr-0.3RE alloys(x=0.1,0.2)in the as-cast state,it was found that the addition of different levels of Zr elements and different rare earth elements had the highest degree of influence on reducing the electrical conductivity and improving the mechanical properties of the alloys: Sc>Ce>La.The Al-0.1Zr-0.3La alloy had the highest electrical conductivity of58.34%IACS;the Al-0.2Zr-0.3Sc alloy had the highest tensile strength of 73.2MPa.Some of the Al-x Zr-0.3RE alloys were hot-rolled,and the best overall performance was the Al-0.1Zr-0.3Sc alloy,whose tensile strength,electrical conductivity,and strength residual rate after heating at 280℃ for 1h are 157.7MPa,57.59%IACS,and90.3%,respectively.The best high-strength,heat-resistant and highly conductive aluminum alloy wire system was determined to be the Al-Zr-Sc alloy.For the Al-Zr-Sc alloy system,the double-stage aging at 250℃ and 400℃ is better than the single-stage aging compared to the single-stage aging.The best aging process for Al-0.18Zr-0.06 Sc alloy is 250℃×24h+400℃×24h,where the microhardness is64.1HV,the electrical conductivity is 60.63%IACS,tensile strength is 152.1MPa,and strength residual rate is 96.4%;the best aging process for Al-0.04Zr-0.12 Sc alloy is250℃×36h+400℃×14h,where the microhardness is 54.0HV,the electrical conductivity is 61.01%IACS,the tensile strength is 145.3MPa,and the strength residual rate is 92.5%.Al-0.18Zr-0.06 Sc alloy wires were prepared by hot extrusion and cold drawing processes.After plastic deformation of the heat-treated alloy,the strength of the alloyed wire was significantly increased,but its electrical conductivity was significantly reduced.The tensile strength of the wire was 203.4MPa and the electrical conductivity was 58.12%IACS.After annealing at 400°C,the tensile strength of the wire decreased with the increase of annealing time and the electrical conductivity gradually increased.When the annealing process is 400℃×18h,the wire has the best overall performance,and its tensile strength,electrical conductivity,elongation and strength residual rate of 280℃×1h are 164.1MPa,61.06%IACS,8.3% and 98.2%respectively.