基于模拟及实验的Cu/NbTi异温包覆挤压界面结合研究

Interface Compatibility During Different-Temperature Cu/NbTi Cladding Extrusion:Simulation and Experiment

提出Cu/NbTi异温包覆挤压,即在塑性变形过程中Cu和NbTi具有不同的温度。Cu/NbTi异温包覆挤压可以有效降低包覆层Cu的变形温度,从而减小包覆层Cu和NbTi芯间的屈服应力差值,有助于二者的协调变形。采用刚粘塑性有限元法模拟凹模入口角分别为60°,120°和180°时Cu/NbTi异温包覆挤压过程,揭示其界面结合情况。模拟结果表明,增大凹模入口角有助于减小包覆层Cu和NbTi芯间的相对伸长量,有益于二者的界面结合。根据有限元模拟优化的工艺参数,进行了Cu/NbTi异温包覆挤压实验,凹模入口角为180°。实验结果表明,该条件下Cu/NbTi包覆挤压过程中金属稳定流动,包覆层Cu和NbTi芯协调变形,二者间相对伸长量较小。实验结果与模拟结果吻合较好。

Different-temperature Cu/NbTi cladding extrusion was put forward where Cu and NbTi are different in temperature during plastic deformation. Different-temperature Cu/NbTi cladding extrusion can significantly lower the deformation temperature of Cu cladding layer so as to reduce the difference in yield stresses between Cu cladding layer and NbTi alloy core, which contributes to accommodating the deformation of the two metals. Rigid viscoplastic finite element method was used to simulate different-temperature Cu/NbTi cladding extrusion in order to reveal the interface compatibility between Cu cladding layer and NbTi alloy core, where various cone angles of bottom die, including 60°, 120° and 180°, were adopted. The results show that increasing the cone angle of bottom die contributes to reducing the relative elongation between Cu cladding layer and NbTi alloy core, which is conducive to the interface bonding between Cu cladding layer and NbTi alloy core. According to the optimal parameters from finite element simulation, Cu/NbTi cladding extrusion die with the cone angle of 180° can be used to implement Cu/NbTi cladding extrusion experiment. The experimental results show that stable flow of metal takes place during Cu/NbTi cladding extrusion, where Cu cladding layer and NbTi alloy core present compatible deformation and the relative elongation between them is small. The experimental results agree well with the simulated ones.