DD6单晶TLP焊用中间层合金研究

Research on Interlayer Alloy used for TLP Bonding of DD6 Single Crystal

DD6单晶是制造航天发动机涡轮叶片用新一代高温合金,TLP焊是实现DD6单晶焊接的有效方法。在合理地设计中间层合金化学成分的基础上,采用单辊急冷法制备出厚度40-60μm,宽约4mm的中间层合金箔,用以进行DD6单晶TLP焊,分析了接头微观组织特征及合金元素的扩散行为。结果表明,快速凝固中间层合金箔成分均匀,组织细小,熔化温度在1 070-1 074℃范围。在焊接温度T=1 200℃,保温时间t=8 h,焊接压力P=0.3 MPa条件下,获得了与单晶母材结合良好、组织致密的扩散连接接头。接头由焊缝中心区、等温凝固区及扩散区3部分组成。随着中间层中合金元素含量的减小,硼元素扩散能力增强,扩散区硼化物残留量趋于减少。

DD6 single crystal is a new generation of superalloy to manufacture aero engine turbine blade, it can be connected effectively by TLP bonding. In this paper, a rapidly solidified interlayer alloy with thickness of 40-60 μm and width of about 4mm was reasonably designed and prepared by a single-roller method, then it was used to conduct TLP bonding of the superalloy and the joint microstructure and diffusion behavior of alloy element was analyzed. The results show that, the microstructures of rapid solidification interlayer alloy are uniform and fine, its melting temperature is in the range of1070~1074 ℃. A diffusion bonding joint with dense bond seam is obtained when the bonding temperature is 1200 ℃ for 12 h at a pressure of 0.3 MPa, which has good combination with base metal. The joint is composed of bond central zone, isothermal solidification zone and diffusion zone.With the decrease of alloy element content in the interlayer alloy, the diffusion ability of boron will be enhanced, and the residues of boride tends to reducing in the diffusion zone.