Effect Of Zr、Si、Mn、Zn On The Heat-resistant Phases And Heat-resistant Properties Of Al-Cu-Mg Heat-resistant Aluminum Alloy

Al-Cu-Mg series heat-resistant aluminum alloys have good weldability,toughness and high temperature creep strength-It is widely used in aerospace structural parts.For example,as a clad sheet for aircraft fuselage.However,the alloy’s working temperature is generally below 150℃,which can’t meet the thermal stability requirements of high-speed aircraft materials.Therefore,the high-temperature mechanical properties of Al-Cu-Mg heat-resistant aluminum alloys need to be improved.A large number of domestic and foreign researches improve the high temperature performance of Al-Cu-Mg heat-resistant aluminum alloys through microelement addition,hoping that it can refine the microstructure and increase the number of heat-resistant strengthening phases.Zr,Si,Mn and Zn are frequently added as microelement in heat-resistant aluminum alloys.There has been extensive research on the addition of a single microelement in Al-Cu-Mg aluminum alloys,while there are few researches on the effect of compound addition of microelement on Al-Cu-Mg aluminum alloys.In this paper,the effects of Zr,Si,Mn and Zn on the heat resistance of Al-Cu-Mg heat-resistant aluminum alloys at alloy microstructure,mechanical properties,room temperature and high temperature mechanical properties were studied by means of OM,SEM and EDS combined with heat exposure test and tensile test.The main conclusions are as follows:(1)The compound addition of Zr,Si,Mn and Zn microelement can refine the dendrite of Al-Cu-Mg alloy ingots.The dendrite of Al-4.54Cu-0.77Mg-0.17Zr-0.35Si-0.28Mn alloy ingot is the smallest.(2)The 250℃ exothermic peak on DSC curves of Al-4.71Cu-0.76Mg alloy and Al-4.52Cu-0.74Mg-0.19Zr alloy is corresponding to the appearance of θ’ phase.The 250℃and 285℃ exothermic peak on DSC curves of Al-4.43Cu-0.73Mg-0.19Zr-0.33Si,Al-4.54Cu-0.77Mg-0.17Zr-0.35Si-0.28Mn and Al-4.53Cu-0.60Mg-0.16Zr-0.35Si-0.28Mn-0.342Zn alloy is corresponding to the appearance of θ’phase and S phase respectively.(3)In 150℃ environment long-term service of heat-resistant aluminum alloy,Al-4.71Cu-0.76Mg alloy sheet should be given priority to use.After heat exposure at 150℃for 200 h,the yield strength,the tensile strength,the strength-ductility balance(TS×EL)of the sheet at room temperature were 313 MPa,422 MPa,18.6%and 7864 MPa·%,and those at 150℃ were 203 MPa,254 MPa,20.0%and 5101 MPa·%.(4)In 200℃ environment long-term service of heat-resistant aluminum alloy,Al-4.54Cu-0.77Mg-0.17Zr-0.35Si-0.28Mn sheet should be given priority to use.After heat exposure at 200℃ for 200 h,the yield strength,the tensile strength,the strength-ductility balance(TS×EL)of Al-4.54Cu-0.77Mg-0.17Zr-0.35Si-0.28Mn sheet at room temperature were 304 MPa,380 MPa,13.2%and 5391 MPa-%,and those at 200℃ were 113MPa,145 MPa,44.2%and 6440 MPa·%.(5)In 250℃ environment long-term service of heat-resistant aluminum alloy,Al-4.54Cu-0.77Mg-0.19Zr alloy sheet should be given priority to use.After heat exposure at 250℃ for 200 h,the yield strength,the tensile strength,the strength-ductility balance(TS×EL)of the sheet at room temperature were 152 MPa,268 MPa,17.7%and 4753 MPa·%,and those at 250℃ were 136 MPa,167 MPa,39.3%and 6565 MPa·%.