Study On Phase Diagram Calculation And Experimental Determination Of Ag-X(X=Pu,Sm,B,Fe),Cu-Cr-Ti And Cu-Cr-Si Systems

Copper and copper alloys with high thermal conductivity,high electrical conductivity,strong corrosion resistance,good processing performance and excellent mechanical properties,were often made into a variety of electronic materials and structural parts and widely used in electrical,electronic,aerospace,military and other fields.In recent years,more and more rigorous demands have been put forward for the conductivity and strength of copper alloys with the rapid development of electronic information industry.However,the increasing the strength of copper alloys often were at the cost of the decreasing of their conductivity.Improvement of the strength of copper alloys and maintaining their high conductivity are important development direction for the modern copper processing industry.A small amount of Ag,which reduced slightly the electrical conductivity and thermal conductivity,can significantly increased the recrystallization temperature and creep strength of copper.The addition of rare earth elements can significantly improve the mechanical properties of copper,refine the grain,and improve the high temperature plasticity of copper.Cu-Cr based alloy is a high strength and high conductivity alloy.Phase equilibrium information of related binary and ternary systems provide important theoretical basis for designing new copper alloys.In the present work,four binary systems Ag-X(X=Pu,Sm,B,Fe)are thermodynamically assessed by means of CALPHAD(CALculation of PHAse Diagrams)method using Thermo-Calc software.By preparing of some key alloys,the isothermal sections of Cu-Cr-Ti and Cu-Cr-Si systems were measured by X-ray diffraction and scanning electron microscopy.The main obtained results are as follows:(1)Based on the experimental phase equilibrium data of Ag-X(X=Pu,Sm,B,Fe)binary systems available in the literature,the solid solution phases,i.e.liquid phase,bcc(εPu,γSm,αFe and δFe),hcp(βSm and εFe),fcc(Ag,δPu and γFe),were modeled using the substitutional solution model,and the binary compounds AgslPu14,Ag2Pu,Ag51Sm14,Ag2Sm,AgSm,AgB2 were described using the sublattice model.The thermodynamic optimization of the Ag-X(X=Sm,Pu,B,Fe)system was carried out by the CALPHAD method.A set of self-consistent thermodynamic parameters were finally obtained for the first time.Compared with the experimental data,the thermodynamic parameters obtained in this work can accurately describe the experimental phase equilibrium data.(2)Based on the experiment-simulated complementary method,12 and 8 key alloys were prepared for the isothermal sections at 800℃ and 600℃,respectively.The phase equilibrium relationships of the Cu-Cr-Ti system were determined by X-ray diffraction(XRD)and scanning electron microscopy(SEM).For the 800℃ isothermal section,4 three-phase regions(i.e.(Cu)+Cr2Ti+Cu4Ti,Cr2Ti+Cu3Ti+(βTi),Cr2Ti+Cu3Ti+CuTi2 and(Cr)+(βTi)+Cu4Ti3)and 3 two-phase regions(i.e.(Cr)+Cu4Ti3,(PTi)+CuTi3 and(βTi)+Cr2Ti)were determined.For the 600℃ isothermal section,3 three-phase regions(i.e.(Cr)+(Cu)+Cu3Ti,CuTi3+Cr2Ti+Ti and Cr+Cu3Ti+Cr2Ti)and 2 two-phase regions(i.e.(Cr)+Cr2Ti and Ti+Cr2Ti)were determined.(3)Based on the experiment-simulated complementary method,7 and 8 key alloys were prepared for the isothermal sections at 700℃ and 800℃ respectively.The phase equilibrium relationships of the Cu-Cr-Si system were determined by X-ray diffraction(XRD)and scanning electron microscopy(SEM).For the 700 0C isothermal section,3 three-phase regions(i.e.(Si)+Cr3Si+Cu4Si,(Cr)+Cu3Si+Cu4Si and(Si)+Cu4Si+CrSi)and 2 two-phase regions(i.e.Cu3Si+CrSi and(Cr)+Cr2Ti)were determined.For the 800℃ isothermal section,1 three-phase regions(i.e(Si)+Cu5S+Cu3S)and 2 two-phase regions(i.e.(Cu)+Cr5Si3 and Cu4Si+CrSi)were determined.Figure[44]table[9]references[96]...