高压扭转制备钨铜梯度材料的仿真和实验研究

Simulation and Experimental Study of W-Cu Gradient Material Processed by High-pressure Torsion

摘要:

采用ABAQUS软件对钨铜材料高压扭转变形进行有限元模拟，分析了扭转变形过程中的应力场分布和应变累积状态，以及压力和温度对界面层应变累积的影响。模拟结果表明，铜在HPT变形过程中为剪切变形的主要承受方，钨未得到充分的剪切变形，界面层应变累积最大；较高的温度和压力有利于界面层的应变累积，但温度的提升效果并不显著，并且高压力和高温度易导致铜反挤和模具失效。在300 ℃、1 GPa、扭转5圈的工艺条件下采用高压扭转工艺制备了界面连接质量良好的钨铜梯度材料。实验结果表明，随着扭转半径的增大，钨和铜的组织均得到显著细化，平均晶粒尺寸分别约为32.6 μm和0.28 μm，并且在界面处出现晶粒尺寸约为4.8 μm的铜组织过渡层；界面处钨和铜结合良好，钨和铜元素的扩散距离分别约为1.74 μm和2.59 μm。铜的显微硬度由初始态的79 Hv提升至131 Hv，界面处钨的显微硬度由初始的347 Hv提高到424 Hv，表明大变形条件下的晶粒细化和缺陷累积有利于界面连接和性能提升。

Abstract:

The deformation behavior of W-Cu material during high-pressure torsion (HPT) was simulated by ABAQUS software. The distributions of stress and equivalent strain, as well as the influence of applied pressure and deformation temperature on the strain accumulation of interface layer were analyzed. The simulation results show that shear deformation is mainly occurred on copper, but has little influence on tungsten, and the strain accumulation of interface layer is the largest. The increase of deformation temperature varying from 300 ℃ to 500 ℃ and applied pressure varying from 1 GPa to 3 GPa have positive effect on the strain accumulation of interface layer, but the higher temperature and applied pressure may lead to the extrusion of copper and the failure of HPT die. At the same time, the W-Cu gradient material with noble bonding interface was obtained through 5 turns of HPT processing under 300 ℃ and 1 GPa, and the diffusion distance of tungsten and copper at the bonding interface is 1.74 μm and 2.59 μm, respectively. The experimental results show that with the increase of torsion radius, the microstructures of W and Cu were significantly refined to 32.6 μm and 0.28 μm, respectively. Also, a transition layer of Cu with grain size of about 4.8 μm can be found at the interface. The microhardness of copper increases from 79 Hv to 131 Hv, and that of tungsten at the interface increases from 347 Hv to 424 Hv, which indicates that grain refinement and defect accumulation under large deformation condition are beneficial to interface bonding and performance improvement.