Study On The Microstructure And Properties Of Cu-Cr-Zr-fe-p Alloys

In this paper, Fe and P elements were added to the traditional spot weldin-g electrode that made by the alloy of Cu-Cr-Zr. The comprehensive performan-ce of spot welding electrode would be improved by the method of poly-eleme-nts strengthening. Four kind alloys was designed in this experimental,which inc-lude Cu-0.6Cr-0.15 Zr, Cu-0.6Cr-0.15Zr-2.5Fe,Cu-0.6Cr-0.15Zr-2.5Fe-0.06 P, Cu-0.6Cr-0.15Zr-0.12Fe-0.06 P. The variation of microstructure and properties of Cu-C r-Zr-Fe-P alloy were studied in different heat treatment processes.The main resu-lts are as follows:(1)When the Fe element was added to Cu-0.6Cr-0.15 Zr alloy under as-cast condition,the hardness of alloy increases,the conductivity of alloy decreases,the grains of Cu-0.6Cr-0.15 Zr alloy was refined.When 2.5wt%Fe was added to Cu-0.6Cr-0.15 Zr alloy, the study found that matrix structure of alloy was changed from columnar grains to equiaxed grains.The structure and properties of alloy was little affected by0.06wt%P added.(2) The effect of different solid temperature on microstructure and properties of Cu-0.6Cr-0.15Zr-2.5Fe-0.06 P alloy was discussed. When solid solution at temperature of 900℃ to 980℃,it was found that alloy electric conductivity decreased with the increasing of solution temperature and the hardness increase with the increase of solution temperature.The electrical conductivity and hardness are respectively 26%IACS and 93.44 HV. After the solid solution treatment at 980℃for 2h,. the properties of different alloy in solid solution state was Compared with as-cast, the conductivity of different composition alloy all decrease and the hardness of Cu-0.6Cr-0.15 Zr and Cu-0.6Cr-0.15Zr-0.12Fe-0.06 P alloy decrease. Due to solid solution strengthening by solution of surplus-phase exceed softening by softening of surplus-phase,the hardness of Cu-0.6Cr-0.15Zr-2.5Fe and Cu-0.6Cr-0.15Zr-2.5Fe-0.06 P alloy increase by solid solution strengthening.(3)After the solid solution treatment at 980℃ for 2h, the microstructure an-d properties of different composition alloy during different aging time and aging temperature were studied.It indicated that the main composition of precipitat-es of Cu-0.6Cr-0.15Zr-0.12Fe-0.06 P during aging was mixture of(CrZrP) and mixture of(Cr ZrFe P) for Cr as main. When the Cu-0.6Cr-0.15Zr-0.12Fe-0.06 Palloy was treated by preferred aging process at 500℃ for 3h,the hardness o-f alloy can reached 154.76 HV, the conductivity of alloy can reached 76.2%IA CS, the softening temperature of alloy reached about 603℃. Compared with the Cu-0.6Cr-0.15 Zr alloy in preferred aging process,the hardness and softening temperature of Cu-0.6Cr-0.15Zr-0.12Fe-0.06 P increased,and the conductivity decr-eased.There were many large precipitated phase in Cu-0.6Cr-0.15Zr-2.5Fe-0.06 P alloy at aging state,the main composition of precipitates of Cu-0.6Cr-0.15Zr-2.5Fe-0.06 P was mixture of(Cr Fe) and(CrZr Fe P)for Fe as main and mixture of Similar atomic percentage(CrFeP),the effect of aging strengthening was not good,the conductivity and hardness of alloy were inferior to Cu-0.6Cr-0.15 Zr in preferred aging process.The aging properties of the alloy was little affected by addition of 0.06wt%P.The overall variation of different composition of alloy in different aging process is that: With the prolonging of the aging time,precipitate-d phase increase and grow up, the conductivity gradually increase and finally tend to be stable; the hardness first increase and decrease after reaching a hard ening peak. When aging temperature is increasing, precipitation phase is rapidly growing,coarsening, the conductivity rapidly increase and reaching the peak of hardening are shorter.(4)the microstructure and property in solution treatment at 980℃ for 2h followed by aging was Compared with as-cast followed by aging,which based on Cu-0.6Cr-0.15Zr-2.5Fe-0.06 P alloy.It was found that the distribution of prec-ipitated phases of alloy based solution treatment at 980℃ for 2h followed by aging was more uniform, the hardness was higher,but both of conductivity have little difference.