Study On The Thermo-mechanical Processing Of High Electrical Conductivity And Heat-resistant Aluminum Alloy

Increasing alloying elements of aluminum alloy conductor can improve its strength, while the electrical conductivity decreased; on the other hand, reducing alloying elements can improve the electrical conductivity, while its strength decreased. Micro-alloying may increase the strength of the alloy under the condition of low alloying elements(namely high electrical conductivity), which provide possibility for solving the contradiction between electrical conductivity and strength. In this paper, adding trace Cu or Mg in Al-Er alloy can improve its strength that maintain the condition of high electrical conductivity, which also can achieve a good matching degree of the electrical conductivity and strength on account of combining solid-solution strengthening, work hardening and precipitation strengthening by a series of thermo-mechanical treatment. The microstructure and properties of Al-Er-Cu and Al-Er-Cu-Mg alloy after different thermo-mechanical treatment were investigated by using Vickers microhardness test, electrical conductivity test, tensile test, X-ray diffraction(XRD) analysis, scanning electron microscope(SEM) observation and transmission electron microscope(TEM) observation. Following conclusions have been drawn from these investigations:The Al-Er-Cu alloy after solid solution treatment has significant isochronal aging strengthening effect compared with the Al-0.21 Cu alloy, while the increase of Cu content has little effect on the increase of the hardness. Large numbers of dispersed and nano-scaled dispersoids formed in Al-0.04Er-0.21 Cu alloy when aged to 400? isochronally after solid solution treatment, which was completely coherent with the Al matrix. Aging to 450? isochronally can precipitate ununiform large size of uneven dispersed dispersoids, which was not coherent with the Al matrix. The cold rolled Al-Er-Cu alloy was annealed at 200? for 48 h, which precipitated lath shaped dispersoids in the matrix and the number of dispersoids increased with the increase of the content of Cu. There are large number of dispersed spherical dispersoids and the lath shaped dispersoids in the matrix when the peak-aged Al-Er-Cu alloy after cold rolled was annealed at 200? for 48 h.For the dilute Al-Er-Cu alloy system, comprehensive comparison of the hardness value and electrical conductivity of different components of Al-Er-Cu alloy after different thermal-mechanical treatment can find that the hardness value increase with the increase of the content of Cu, while the electrical conductivity decreased. As-solution Al-Er-Cu and peak-aged Al-Er-Cu alloy after cold rolled were annealed at 200? for appropriate annealing time, which had a higher hardness and electrical conductivity. As-solution Al-0.04Er-0.43 Cu alloy after cold rolled has tensile strength up to 251 Mpa and electrical conductivity of 57.31%IACS. It has tensile strength decrease to 205 Mpa and electrical conductivity increase to 59.47%IACS after annealed at 200? for 24 h. It has electrical conductivity increase to 59.47%IACS after two-stage aging(300?/2h+200?/24h)For Al-Er-Cu-Mg alloy system, comprehensive comparison of the hardness value and electrical conductivity of different components of Al-Er-Cu-Mg alloy after different thermal-mechanical treatment can find that Al-Er-Cu-Mg alloy were annealed at 200? for appropriate annealing time has a higher hardness and electrical conductivity. Cold rolled Al-0.02Er-0.43Cu-0.56 Mg alloy was annealed at 200? for 24 h, which has tensile strength up to 240 Mpa and electrical conductivity of 58.54%IACS. Cold rolled Al-0.04Er-0.43Cu-0.56 Mg alloy was annealed at 200? for 24 h, which has tensile strength up to 292 Mpa and electrical conductivity of 54.87%IACS. According to the strength survival rate of Al-Er-Cu and Al-Er-Cu-Mg alloy was annealed at 230? for 1h and cooled to room temperature, it can be judged that the heat resistance of the alloy is good.