| Cu-Fe-Mg-Ti and Cu-Fe-Mg-Co alloys are ageing copper alloys with excellent mechanical properties,which can be widely used in railroad transportation,electrical and electronic industries.Due to the addition of Fe,Ti,Co elements have a strengthening effect on the alloy,and its impact on the conductivity of the alloy is high.In view of this,the composition ratios and process parameters of Cu-Fe-Mg-Ti and Cu-Fe-Mg-Co alloys are optimized in this paper to obtain the alloy products with the best overall performance.To control the atomic ratios（1︰1,1︰2,2︰1）of Fe,Ti and Fe,Co elements in Cu-Fe-Mg-Ti and Cu-Fe-Mg-Co alloys,and the effects of different Fe︰Ti and Fe︰Co ratios on the organization and properties of Cu-Fe-Mg-Ti and Cu-Fe-Mg-Co alloys at each stage of the heat treatment process were investigated.High-temperature softening resistance tests and frictional wear tests were also conducted to elucidate the mechanism of high-temperature softening and frictional wear mechanism of Cu-Fe-Mg-Ti.The results of the study are as follows:（1）After Cu-Fe-Mg-Ti（Co）alloy treated by the"casting-hot rolling-solid solution-aging"process.Three groups of Cu-Fe-Mg-Ti alloys with different Fe︰Ti ratios,the best overall performance of the alloy was achieved when Fe︰Ti ratios was2︰1.Meanwhile,Cu-Fe-Mg-Co alloys with different Fe︰Co ratios,and the best overall performance of the alloy was achieved when the Fe︰Co ratios was 1︰1.（2）The three alloys with different Fe︰Ti and Fe︰Co ratios（1︰1,1︰2,2︰1）were analyzed by transmission electron microscopy,and the precipitated phase of FT12 alloy was spherical,Fe2Ti phase,which is a hexagonal crystal system,the orientation relationship between the precipitated particles and the matrix is as follows:[120]Fe2Ti//[1?10]Cu.FT11 and FT12 alloys are also Fe2Ti precipitated phases with uniform tissue distribution.The spherical shape of the precipitated particles of FC21alloy is Cu Mg2 phase,which is an orthogonal crystal system with a[343]Cu Mg2//[1?21]Cu site-directed relationship with the matrix.The precipitated phase of FC11 alloy and FC12 alloy are Cu Mg2 precipitated phase,which has a uniform tissue distribution and a regular spherical shape.（3）The effect of cold deformation process on the tissue properties of Cu-Fe-Mg-Ti and Cu-Fe-Mg-Co alloys were investigated,and the cold deformation process significantly improved the properties of Cu-Fe-Mg-Ti and Cu-Fe-Mg-Co alloys.After cold deformation treatment with 70%deformation,the peak ageing hardness of FT12 alloy is 189.5 HV and the electrical conductivity is 44.2%IACS.The FT11 alloy had an aging peak hardness of 173.9 HV and an electrical conductivity of 51.3%IACS,and the FT21 alloy ha d an aging peak hardness of 166.5HV and an electrical conductivity of 64.1%IACS.Meanwhile,after FC12,FC11 and FC21 alloys were cold rolled at 70%,the best overall performance of the alloy was achieved when the Fe︰Co ratios is 1︰1.,with a maximum hardness value of 162.2HV and an electrical conductivity of 45.2%IACS.（4）The main softening mechanisms of the alloys at low temperatures are reversion and partial recrystallization nucleation,and at high temperatures are:growth of recrystallized grains and coarsening of precipitated phases.For the Cu-Fe-Mg-Ti alloys with different Fe︰Ti ratios,the best softening temperature resistance is 600℃when the Fe︰Ti ratios is 2︰1,and for Cu-Fe-Mg-Co alloys with different Fe︰Co ratios,the best softening temperature resistance is 480℃when the Fe︰Co ratios is 1︰1.The frictional wear mechanism of Cu-Fe-Mg-Ti alloys with different Fe︰Ti ratios and Cu-Fe-Mg-Co alloys with different Fe︰Co ratios were all adhesive wear. |
