Study On Microstructure And Properties Of Al-Cu-Sc-Zr Electrical Materials

With the rapid development of national economy,aluminum alloy electrical materials for overhead power transmission are facing higher requirements.In this thesis,two alloys,Al-Cu-Sc and Al-Cu-Sc-Zr,were prepared by adding Cu,Sc,Zr and other alloying elements with industrial pure aluminum as the main raw material,and the effects of the addition of alloying elements and aging heat treatment regime on their microstructure and properties were systematically investigated.The main findings are as follows.(1)Using the Central Composite Design(CCD)method in the response surface method,the better composition of the Al-Cu-Sc ternary alloy was determined to be w(Cu)=0.35%and w(Sc)=0.24%,and the better aging heat treatment process was determined to be 330℃×15 h.The conductivity of the alloy in the peak aging state was 60.2%IACS and the tensile strength was 164.85 MPa.The distribution of the elements in the prepared alloy is uniform and diffuse,and there is no segregation in the composition.Compared with the alloy prepared under other conditions,the grain size of the alloy was significantly refined and the number of fine second-phase particles Al3Sc diffusely distributed in the tissue was increased,which led to the significant improvement of its mechanical properties.(2)The better composition of Al-Cu-Sc-Zr quaternary alloy is determined as w(Cu)=0.35%,w(Sc)=0.1 8%,w(Zr)=0.06%,and the better aging heat treatment process is 390℃×15 h.The conductivity of the alloy in the peak aging state is 60.4%IACS,and the tensile strength can be increased to 169.46 MPa.The alloy microstructure grain size is small and uniform,the distribution of each alloy element is diffuse without component segregation,the second phase particles Al3(Sc,Zr)phase which is highly co-grid with the matrix is uniform and small,the tensile fracture is small and shallow.Compared with the Al-Cu-Sc ternary alloy,the added Zr element can slow down the growth rate of the precipitated second-phase particles and effectively improve the thermal stability of the alloy.