Effect Of Ni,Mn And Sc On The Microstructure And Properties Of ZL207

As a heat-resistant Al-Cu alloy,ZL207 has better high-temperature performance compared with other existing cast aluminum alloys.It is commonly used in small and medium-sized aircraft parts under air pressure and hydraulic pressure at 300 ? 400 ?.In order to imporve the alloy structure and imporve its mechanical properties,given that this alloy belongs to non solution strengthening aluminum alloy,three metal elements,Ni,Mn,Sc,were added to the original alloy composition,the orthogonal test was used to study the effect of adding elements on the microhardness and high temperature properties of the alloy,and the best combination of elements was determined.Optical microscope,electron microscope and X-ray diffractometer were used to observe the microstructure and phase of the alloys.The mechanical properties of the alloys were tested by microhardness tester and universal tensile machine.The results show that the microstructure of as cast and heat treated alloys is composed of matrix,dendritic phase and massive phase.In the as cast state,Sc has the greatest effect on the second phase content,followed by Mn,and least affected by Ni.The optimal element combination is 1.5 Ni-0.2 Mn-0.3 Sc.In the state of heat treatment,the primary and secondary order of influence on the second phase content is Ni,Sc and Mn,and the best combination is 1.5 Ni-0.2 Mn-0.3 Sc.For the as cast hardness of the alloy,Mn has the greatest influence,followed by Ni,and the least affected is Sc.the optimal combination of elements is 1.5 Ni-0.1 Mn-0.3 Sc.The results show that the order of influence on the hardness of heat-treated alloy is Sc,Mn,Ni,and the optimal element combination is 1.5 Ni-0.1 Mn-0.2 Sc.With respect to exploring the effect of adding metal elements on the hightemperature properties of alloys,at 300?,the primary and secondary order of the tensile strength of alloys is Sc,Mn,Ni,and the optimal element combination is 1 Ni-0.1 Mn-0.2 Sc.The primary and secondary order of alloy elongation is Sc,Mn,Ni,and the optimal element combination is 1.5 Ni-0.3 Mn-0.2 Sc.At 350 ?,Mn,Ni and Sc are the primary and secondary elements affecting the tensile strength of the alloy,and the optimal element combination is 1 Ni-0.1 Mn-0.2Sc.The results show that Ni,Sc and Mn are the primary and secondary factors affecting the elongation of the alloy,and the optimal element combination is 1 Ni-0.3Mn-0.3 Sc.At 400 ?,Mn,Ni and Sc are the primary and secondary elements affecting the tensile strength of the alloy,and the optimal element combination is 1 Ni-0.1 Mn-0.2Sc.The results show that the order of influence on elongation is Sc,Ni,Mn,and the optimal element combination is 1 Ni-0.3 Mn-0.3 Sc.