Ti_2AlNb基合金电子束焊接头的显微组织

利用透射电子显微镜和能谱,研究电子束焊接过程中Ti_2AlNb基合金显微组织演变过程以及焊缝区组成、焊后热处理对接头显微组织的影响.结果表明:焊接过程中焊缝区Al元素损失较为严重,这有利于B_2相的形成而不利于O相的形成,使得接头焊缝区主要由B_2和α_2两相组成;在随后的热处理过程中,焊缝区的B_2相转变为β相和板条状的O相,使焊缝区由α_2、O和β相组成.

Microstructure of Ti_2AlNb Joint Produced by Electron Beam Welding

The microstructure and composition of Ti_2AlNb joints fabricated by electron beam welding technique were investigated by transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS). The effect of the composition of the welded zone and heat treatment after welding on the microstructure of the joint was also studied. Results showed that there was a great weight loss of Al element in the joint during welding, which was beneficial to the formation of B_2 phase but O phase. The as-welded joint was composed of B_2 and α_2 phases, while the joint after heat treatment was of α_2, O and β phases, which indicated that the following phase transformation of B_2 to β and O occurred.