To investigate the effect of grain refinement on the material properties of recently developed Al-25 Zn-3 Cu based alloys,Al-25 Zn-3 Cu,Al-25 Zn-3 Cu-0.01 Ti,Al-25 Zn-3 Cu-3 Si and Al-25 Zn-3 Cu-3 Si-0.01 Ti alloys we...To investigate the effect of grain refinement on the material properties of recently developed Al-25 Zn-3 Cu based alloys,Al-25 Zn-3 Cu,Al-25 Zn-3 Cu-0.01 Ti,Al-25 Zn-3 Cu-3 Si and Al-25 Zn-3 Cu-3 Si-0.01 Ti alloys were produced by permanent mold casting method.Microstructures of the alloys were examined by SEM.Hardness and mechanical properties of the alloys were determined by Brinell method and tensile tests,respectively.Tribological characteristics of the alloys were investigated by a ball-on-disc type test machine.Corrosion properties of the alloys were examined by an electrochemical corrosion experimental setup.It was observed that microstructure of the ternary A1-25 Zn-3 Cu alloy consisted ofα,α+ηandθ(Al2Cu)phases.It was also observed that the addition of 3 wt.%Si to A1-25Zn-3Cu alloy resulted in the formation of silicon particles in its microstructure.The addition of 0.01 wt.%Ti to the Al-25Zn-3Cu and Al-25 Zn-3 Cu-3 Si alloys caused a decrement in grain size by approximately 20%and 39%and an increment in hardness from HRB 130 to 137 and from HRB 141 to 156,respectively.Yield strengths of these alloys increased from 278 to 297 MPa and from 320 to 336 MPa while their tensile strengths increased from 317 to 340 MPa and from 334 to 352 MPa.Wear resistance of the alloys increased,but corrosion resistance decreased with titanium addition.展开更多
Similar friction welded joints of AA-7005 aluminum rods were fabricated using different combinations of process parameters such as friction pressure(1.0, 1.5 and 2.0 MPa) and friction time(10, 15 and 20 s). Interfacia...Similar friction welded joints of AA-7005 aluminum rods were fabricated using different combinations of process parameters such as friction pressure(1.0, 1.5 and 2.0 MPa) and friction time(10, 15 and 20 s). Interfacial microstructure and formation of intermetallic compounds at the joint interface were evaluated via scanning electron microscopy(SEM) equipped with energy dispersive spectrum(EDS), and optical microscopy(OM). Microstructural observations reveal the formation of intermetallic phases during the welding process which cannot be extruded from the interface. Theses phases influence the tensile strength of the resultant joints. From the tensile characteristics viewpoint, the greatest tensile strength value of 365 MPa is obtained at 1.5 MPa and 15 s. Finally, the role of microstructural features on tensile strength of resultant joints is discussed.展开更多
In order to determine the effect of heat treatment on the mechanical and wear properties of Zn−40Al−2Cu−2Si alloy,different heat treatments including homogenization followed by air-cooling(H1),homogenization followed ...In order to determine the effect of heat treatment on the mechanical and wear properties of Zn−40Al−2Cu−2Si alloy,different heat treatments including homogenization followed by air-cooling(H1),homogenization followed by furnace-cooling(H2),stabilization(T5)and quench−aging(T6 and T7)were applied.The effects of these heat treatments on the mechanical and tribological properties of the alloy were studied by metallography and,mechanical and wear tests in comparison with SAE 65 bronze.The wear tests were performed using a block on cylinder type test apparatus.The hardness,tensile strength and compressive strength of the alloy increase by the application of H1 and T6 heat treatments,and all the heat treatments except T6,increase its elongation to fracture.H1,T5 and T6 heat treatments cause a reduction in friction coefficient and wear volume of the alloy.However,this alloy exhibits the lowest friction coefficient and wear volume after T6 heat treatment.Therefore,T6 heat treatment appears to be the best process for the lubricated tribological applications of this alloy at a pressure of 14 MPa.However,Zn−40Al−2Cu−2Si alloy in the as-cast and heat-treated conditions shows lower wear loss or higher wear resistance than the bronze.展开更多
文摘To investigate the effect of grain refinement on the material properties of recently developed Al-25 Zn-3 Cu based alloys,Al-25 Zn-3 Cu,Al-25 Zn-3 Cu-0.01 Ti,Al-25 Zn-3 Cu-3 Si and Al-25 Zn-3 Cu-3 Si-0.01 Ti alloys were produced by permanent mold casting method.Microstructures of the alloys were examined by SEM.Hardness and mechanical properties of the alloys were determined by Brinell method and tensile tests,respectively.Tribological characteristics of the alloys were investigated by a ball-on-disc type test machine.Corrosion properties of the alloys were examined by an electrochemical corrosion experimental setup.It was observed that microstructure of the ternary A1-25 Zn-3 Cu alloy consisted ofα,α+ηandθ(Al2Cu)phases.It was also observed that the addition of 3 wt.%Si to A1-25Zn-3Cu alloy resulted in the formation of silicon particles in its microstructure.The addition of 0.01 wt.%Ti to the Al-25Zn-3Cu and Al-25 Zn-3 Cu-3 Si alloys caused a decrement in grain size by approximately 20%and 39%and an increment in hardness from HRB 130 to 137 and from HRB 141 to 156,respectively.Yield strengths of these alloys increased from 278 to 297 MPa and from 320 to 336 MPa while their tensile strengths increased from 317 to 340 MPa and from 334 to 352 MPa.Wear resistance of the alloys increased,but corrosion resistance decreased with titanium addition.
文摘Similar friction welded joints of AA-7005 aluminum rods were fabricated using different combinations of process parameters such as friction pressure(1.0, 1.5 and 2.0 MPa) and friction time(10, 15 and 20 s). Interfacial microstructure and formation of intermetallic compounds at the joint interface were evaluated via scanning electron microscopy(SEM) equipped with energy dispersive spectrum(EDS), and optical microscopy(OM). Microstructural observations reveal the formation of intermetallic phases during the welding process which cannot be extruded from the interface. Theses phases influence the tensile strength of the resultant joints. From the tensile characteristics viewpoint, the greatest tensile strength value of 365 MPa is obtained at 1.5 MPa and 15 s. Finally, the role of microstructural features on tensile strength of resultant joints is discussed.
基金This work was supported by Scientific Research Projects Coordination Unit of Karadeniz Technical University,Turkey(No.2008.112.03.1).
文摘In order to determine the effect of heat treatment on the mechanical and wear properties of Zn−40Al−2Cu−2Si alloy,different heat treatments including homogenization followed by air-cooling(H1),homogenization followed by furnace-cooling(H2),stabilization(T5)and quench−aging(T6 and T7)were applied.The effects of these heat treatments on the mechanical and tribological properties of the alloy were studied by metallography and,mechanical and wear tests in comparison with SAE 65 bronze.The wear tests were performed using a block on cylinder type test apparatus.The hardness,tensile strength and compressive strength of the alloy increase by the application of H1 and T6 heat treatments,and all the heat treatments except T6,increase its elongation to fracture.H1,T5 and T6 heat treatments cause a reduction in friction coefficient and wear volume of the alloy.However,this alloy exhibits the lowest friction coefficient and wear volume after T6 heat treatment.Therefore,T6 heat treatment appears to be the best process for the lubricated tribological applications of this alloy at a pressure of 14 MPa.However,Zn−40Al−2Cu−2Si alloy in the as-cast and heat-treated conditions shows lower wear loss or higher wear resistance than the bronze.
