应变速率和变形量对合金元素在Ti_3Al和TC11焊接界面上扩散的影响

Effects of strain rate and deformation amount on diffusion of alloying elements at Ti_3Al and TC11 welding interface

研究了Ti3Al基合金与TC11钛合金采用不同参数的电子束焊接的双合金件,经近等温锻造和热处理后,近等温锻造工艺参数对合金元素在焊接界面上扩散的影响。结果表明,应变速率和变形量对不同参数焊接的双合金件焊接界面合金元素扩散的影响类似,均随着应变速率的降低及变形量的增大扩散更充分。但当变形20%时,合金元素以沿晶界扩散的管道机制为主;当变形40%时,扩散以晶间扩散机制为主。此外,Ti元素在焊缝区的反常扩散是由于Ti原子的点阵位置被从Ti3Al侧扩散而来的Nb原子所占据,被替代的Ti原子从DO19六方有序结构中扩散出来聚集所造成。

Ti3Al-based alloy and TC11 titanium alloy were joined by electron beam welding in different welding currents,and then the Ti3Al and TC11 dual alloy was processed by forging and heat treatment.The effects of strain rate and deformation amount on diffusion of alloying elements at the welding interface were investigated.The results show that the alloying elements diffuse sufficiently at the welding interface as the strain rate decreases and the deformation amount increases.When the specimen is deformed by 20%,the alloying elements diffuse mainly along grain boundary by tube mechanism.However,the mechanism of intercrystalline diffusion for alloying elements prevails as the specimen is deformed by 40%. In addition,the reason for the abnormal diffusion of Ti element in the weld zone is that the position of the Ti atom in the weld zone is occupied by the Nb atom diffusing from Ti3Al alloy base.Therefore,these Ti atoms diffuse out from DO19（hexagonal）crystal structure and accumulate together.