Study On The Composition And Heat Treatment Process Of Al-Cu-Mg-Ag High Strength And Heat Resistant Cast Aluminum Alloy

The material thermodynamic calculation method is adopted in this paper.The stability of the precipitated phases of Al-Cu-Mg alloy and composition of the elements in the precipitated phase were studied.In normal temperature and high temperature(300 ℃)conditions,The content of Cu,Mg,Mn and the change of Cu/Mg value affect the proportion of each precipitate in Al-Cu-Mg alloy.The phase change in the process of casting Al-Cu-Mg alloy was studied by phase diagram calculation.The results of phase diagram calculation are verified by means of differential scanning calorimetry(DSC).According to the calculated alloy phase diagram,different heat treatment process is designed.The effects of different solid solution treatment processes such as the series,temperature and time on the mechanical properties of the alloy were simulated by means of thermodynamics calculation.The heat treatment process of Al-Cu-Mg alloy was obtained.After adding Ag element to al-cu-mg alloy,the main strengthening phase in the alloy from theta precipitated phase shift Ω strengthening phase,which make the alloy has better heat resistance.However,it is difficult to calculate the effect of various alloy elements on Al-Cu-Mg-Ag alloy by using the existing material calculation method.Therefore the effects of Mg,Ag and Ti on the mechanical properties of Al-Cu-Mg-Ag alloy at normal temperature and high temperature were studied by single factor experiment.The composition range of Al-Cu-Mg-Ag alloy was obtained.The heat treatment process of Al-Cu-Mg alloy is based on calculated phase diagram.The heat treatment parameters of Al-Cu-Mg-Ag alloy were studied by single factor experiment.Experimental process is divided into two parts,one is for solid solution heat treatment of solid solution series,upper limit of solid solution temperature,solution time,the second is for alloy aging heat treatment temperature and time of the process parameters for singlefactor experiment,the identify of Al-Cu-Mg-Ag alloy heat treatment process parameters of the optimal value.After obtaining better Al-Cu-Mg-Ag alloy composition range and heat treatment process parameters,The alloy was tested by sand casting and compared with ZL205 alloy,The casting’s defect types,defect distribution and mechanical properties of the alloy castings were obtained.Some basic work is done for the further engineering application of the alloy.An Al-Cu-Mg-Ag alloy was developed.The tensile strength of the alloy is more than 200 MPa under 300 ℃.