| Cu-Ni-Al alloys have excellent mechanical properties, corrosion resistance and wear resistance, which have been widely used in marine, petroleum, chemical and aerospace industries. In this paper, the effect of Cr, Si andy Al on the microstructure and properties of hot-extruded Cu-17Ni-1.0Fe alloys were investigated by optical microscope, scanning electronic microscope, transmission electronic microscope, tensile tests and friction and wear tests. In addition, comparative studies had been taken between the designed alloy and as-cast ZBAl16-3-1.5 alloy. The main conclusions are summarized as follows:(1) Cr is existed as coarse rod-like Cr-rich phase in as-cast and as-annealed condition, it transforms into tiny rod shaped after hot extrusion. In the as-cast condition, Si exists as disk-like or rod-like Si-rich phase. After annealing, Si-rich phase dissolves into the matrix, precipitates tiny filaments-like and particle-like Si-rich phase in grain boundary. After hot extrusion, in addition the particle-like Si-rich phase is formed in grain boundary, the nanoscale flake-like β-Ni3 Si and δ-Ni2 Si phase have been precipitated in grain interior. The main phases is spherical-like γ-Ni3 Al in matrix, and filaments-like, layer-like and particle-like γ-Ni3 Al and β-Ni Al mixed phase in grain boundary.(2) Both Cr and Si can promote the recrystallization processing of the alloy during the hot extrusion but the effect of Si is stronger than Cr. This can be attributed to the β-Ni3 Si and δ-Ni2 Si phases are more than Cr-rich phase during the hot extrusion. Consequently, the alloys with Si addition get much driving force of recrystallization. For the same reason, the quantity and dispersion of second phases precipitate in the alloys with the addition of Si are more than the addition that of Cr. So the second phase strengthening effect of the alloy with addition of Si is better than that of Cr.(3) The effect of extrusion temperature on the microstructure and properties of Cu-17Ni-1.5Al-1.0Fe-0.5Cr-0.5Si alloy had been studied. The results show that the alloys cause incomplete recrystallization with the extrusion temperature range of 925 and 975℃ ℃, fully recrystallization of 1000 ℃and 1050℃, growing recrystallized grains of 1000 ℃and 1050℃ when the extrusion ratio is 17.4. The optimum mechanical property and tribological property of the alloys can be obtained with the extrusion temperature range of 1000℃ and 1050℃.(4) The effect of extrusion ratio on the microstructure and properties of Cu-17Ni-1.5Al-1.0Fe-0.5Cr-0.5Si alloy have been studied. The results show that the alloys cause incomplete recrystallization with the extrusion ratio range of 6.2 and 9.8, fully recrystallization of 12.8 and 17.4, incomplete recrystallization again with of 25 when extrusion temperature is 1025℃. The optimum mechanical property and tribological property of the alloys can be obtained with the extrusion ratio range of 12.8 and17.4.(5) Compared to the tribological property of Cu-17Ni-1.5Al-1.0Fe-0.5Cr-0.5Si alloy which prepared at extrusion temperature 1025℃ and extrusion ratio 17.4 and ZBAl16-3-1.5. The results show that the wear resistance of the designed alloy is worse than ZBAl16-3-1.5 under the condition of low load during dry sliding, but is almost the same as that of ZBAl16-3-1.5 under the condition of high load. During oil-lubricated sliding, whether low load or high load, the wear resistance of the designed alloy is worse than ZBAl16-3-1.5. |
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