Abstract:

The effects of four solid-solution treatments on the microstructure and properties of Al-5.6Cu-1.7Mg-0.2Zr-0.1Sr-0.6Ti alloy were studied herein by metallographic structure analysis,SEM(Scanning Electron Microscope) analysis、X-Ray Diffraction,hardness,conductivity,room temperature tensile properties, elongation after fracture and intergranular corrosion resistance. The results show that the grain size increases and with an increase in the solution temperature. The size and quantity of insoluble phase in the alloy decrease with increasing solution temperature when the temperature is less than 520 ℃. When the solid treatment is 510 ℃ for 2 h and then at 520 ℃ for 2 h, the insoluble phase in the alloy begins to increase, and the alloy appears slight overburning, the elongation after fracture and intergranular corrosion resistance become worse, but the tensile strength reaches the highest as 490.14 MPa. The dislocation strength and dislocation contribution decrease with an increase in the solution temperature. The strength effect in the alloy is mainly attributed to the solution strengthening and aging precipitation strengthening.Two different solid-solution treatments (route a:490 ℃ for 2 h and then at 500 ℃ for 2 h; route b: 500 ℃ for 2 h and then at 510 ℃ for 2 h) both can guarantee the mechanical properties(strength and elongation) and intergranular corrosion resistance of the alloy under T6 aging are good; therefore,both of the solid-solution treatments are suitable for preparing Al-5.6Cu-1.7Mg-0.2Zr-0.1Sr-0.6Ti alloy.

Key words: Al-5.6Cu-1.7Mg-0.2Zr-0.1Sr-0.6Ti alloy, solid-solution treatment, microstructure, mechanical properties, intergranular corrosion