| Cu-Cr-Zr alloy is a promising high-performance copper alloys,with high strength and thermal conductivity properties, widely used in electrical motors, aerospace, communications, transportation and other high-tech fields.With the rapid development of China’s electrification, the performance requirements of high-performance copper alloy is increasing.Therefore, it is of great significance to research the thermomechanical and aging treatment and the relations of microstructure and properties of high-performance copper alloy.In this thesis,the influence of working methods and heat treatment condition on the microstructure,harndess and conductivity of Cu-Cr-Zr alloy was investigated by optical microscopy,SEM, hardness test and electrical resistance test.Meanwhile,the mechanism of the influence was discussed.The results show that:The optimal solid solution temperature of Cu-Cr-Zr alloy is980℃.After solution treatment at980℃for1h,aging at400℃to500℃, finding that the best aging process conditions were aged at500℃for4h,and the hardness and conductivity were136.5HV and75.2%IACS. with the aging time in the aging process,in the start stage, hardness of the alloy increases rapidly.When reaching a peak value,the hardness begins to decrease with the aging time. the higher the temperature, the shorter the time the hardness rise to the peak.at the earlier stage,the conductivity increases rapidly,it tendes to be stable with the aging time.On the basis of the variation analysis of the conductivity of Cu-Cr-Zr alloy process,there is a linear relationship between the amount of conductivity increase and the new phase precipitation amount. The aging process of the Cu-Cr-Zr alloy is described using phase transformation kinetics Avrami empirical equation,and the alloy transformation kinetics equation and conductivity equation can be dedued in each aging temperature. The isothermal transformation (TTT) curve is drawn by calculating the kinetics of the alloy.Cold deformation of the Cu-Cr-Zr solution alloy before aging, can promote the second phase precipitates of the early aging of,and conductivity can recover quickly, while the alloy after cold deformation, resulting in a high density of dislocations, and the second phase is present dispersed,tafter aging he higher microhardness can be obtained.After Solution-aging-cold drawing,the hardness increased more significantly, the conductivity decreased. Then Annealing at450℃for1h, the conductivity increased and hardness decreased slightly.Artificial neural network models of aging process for Cu-Cr-Zr alloy are established by BP neural network.It is expressed by three-dimensional map,and can be drawn aging temperature and aging time on the hardness and conductivity law, laid the foundation for the optimization of process parameters. |
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