Research On The Heat Resistance Of SiC_w/Al-Cu-Mg-Ag Composites

Traditional Al-Cu-Mg alloys are widely used for high strength and good heat resistance,but such alloys are used above 200?due to rapid degradation of mechanical properties,which is difficult to meet the aerospace requirements for the new generation of heat-resistant materials.Al-Cu-Mg-Ag alloy with Al-Cu-Mg alloy can produce the?phase better stable and improve the heat resistance of the alloy.In addition,the forced addition of the aluminum alloy with high strength and high heat and stable reinforced phase to form a heat-resistant aluminum-based composite material can further improve the heat resistance performance of the alloy.The Al-Cu-Mg-Ag alloy with different Ag content was prepared by pressure casting process,and studied the influence on mechanical properties,room temperature,high temperature tensile properties and thermal stability,and optimized the Ag content in Al-Cu-Mg-Ag alloy after thermal extrusion.Based on this,20vol%SiC_w/Al-Cu-Mg-Ag composite was prepared by the pressure immersion process to study the thermal processing deformation behavior of the composite materials and guide the thermal extrusion of the composite,and study the influence and law of SiC_w and its orientation on the room temperature and thermal mechanical properties of the composite.Eliminate polarization of alloy elements under 500?after 9h,difficulty of main alloy elements Cu>Mg>Ag.The extrusion Al-Cu-Mg-Ag alloy can be prepared when extrusion temperature at 450?and extrusion ratio is 25:1,with the outgoing phase arranged along the extrusion direction.The thermal resistance of Al-Cu-Mg-Ag alloy with different Ag content increased with Ag content,and the Al-Cu-Mg-Ag alloy with 0.8wt%showed the best comprehensive performance.The peak limitation hardness of the Al-Cu-Mg-0.8Ag alloy is 218HV,increased by 43.4%over 152 HV of the peak limitation hardness of the 2024aluminum alloy.The yield strength and tensile strength of Al-Cu-Mg-0.8Ag alloy are 350MPa and 511MPa,respectively at room temperature.The yield strength and tensile strength of Al-Cu-Mg-0.8Ag alloy are 313 MPa and 438MPa,respectively at 200?.The yield strength and tensile strength of Al-Cu-Mg-0.8Ag alloy are 270 MPa and 372MPa,respectively at 250?.The yield strength and tensile strength of Al-Cu-Mg-0.8Ag alloy are 215 MPa and 227MPa,respectively at 300?.Exuded Al-Cu-Mg-Ag alloy with Ag content of 0.8wt%showed optimum thermal stability during thermal exposure at 250?,stabilized at thermal exposure time above100h and the yield strength and tensile strength of Al-Cu-Mg-0.8Ag alloy are 183 MPa and 288MPa after thermal exposure of 270h at 250?.The thermal deformation activation energy of the SiC_w/Al-Cu-Mg-Ag composite is 188.43k J/mol,and the safe processing area of the composite is(strain rate 0.001?0.01s^-1,with a processing temperature of 480?500?).Good-state composite extrusion rod can be prepared at an extrusion temperature of 490?and an extrusion ratio of 16:1.The thermal extrusion deformation breaks the bulk in the composite material and arranges the fiber tissue in the extrusion direction,where the crystal must be distributed along the extrusion direction,and the matrix grain forms an obvious<111>orientation texture.The hardness of composite material is improved compared with Al-Cu-Mg-Ag alloy,and its peak limitation hardness is 238HV.SiC_w greatly weakens the limitation reinforcement effect of reinforcement phase in matrix alloy.At temperatures below 300?,SiC_w significantly improved the alloy strength,but the deformation between the matrix and the enhancement showed low plasticity.At 300?,the matrix alloy softened rapidly in the composite,causing the material failure of the interface between SiC_w and the matrix,and SiC_w could not significantly improve the mechanical properties of the composite material.The whiskers exhibit high stress sensitivity in the extruded SiC_w/Al-Cu-Mg-Ag complexes,and the mechanical properties show anisotropy.At a temperature below300?,the crystals arranged in the vertical pressure direction of the composite must show the better stability during the compression process,showing the better compression mechanical performance in the vertical extrusion direction of the composite.When the temperature reaches 300?,the aluminum alloy matrix softening,the crystal with different orientations of the composite deformation cannot carry effectively,and the influence of the grain orientation on the mechanical properties of the composite material disappears.