Aging And Hot Deformation Behavior Of Cu-Zr(-RE)alloy With High Strength And High Conductivity

Zirconium bronze is a copper alloy with a certain amount of zirconium.As for its high quality electrical conductivity,high stress resistance and appropriate strength at high temperature,it is widely used in high temperature surroundings,such as power transmission device,high temperature switch,resistance welding,and so on.The Cu-0.2%Zr(-0.15%RE)alloys were cast in a vacuum induction furnace.Hot compression tests were conducted by using the Gleeble-1500 D thermo-mechanical simulator.Hot deformation behavior for the alloys was analyzed and the hot processing maps were established.The critical strain for the occurrence of DRX were determined based on the strain hardening rate.Based on the effects of strain rate and temperature on the stress,a constitutive model has been proposed,and the accuracy of the model was examined.Aging treatment for Cu-0.2%Zr(-0.15%RE)alloys were conducted under the different conditions.The effects of cold deformation,aging temperature and time on the electrical conductivity and microhardness were studied,respectively.The phase transformation kinetics,electrical equations and TTT curves for the Cu-0.2%Zr(-0.15%RE)alloys were established.The results show that Cu-0.2%Zr(-0.15%RE)alloys are temperature and strain rate sensitive alloys.Dynamic recovery and recrystallization are the main softening mechanism during the thermal deformation.The addition of rare earth can promote the occurrence of dynamic recrystallization and improve the hot deformation activation energy of alloy.The constitutive equations has a high accuracy with the correlation coefficients of constitutive equations were above 0.95.The optimum processing conditions for alloys are at low strain rate and high temperature.After aging treatment,the hardness and electrical conductivity is improved.The results show that the Cu-0.2%Zr alloy has the best performance at 500 °C for 1 h after 60% deformation under different conditions.The hardness is 136 HV and the conductivity is 95.03% IACS.The precipitation phase is Cu10Zr7.At 500 °C aging,the precipitation phase is the earliest and the precipitation time is the shortest by TTT curve.With the addition of rare earth,conductivity of the alloy decreases slightly,but the hardness is greatly improved.