标准热处理对采用BNi-9焊料的瞬时液相连接IN-738LC高温合金的影响

研究标准热处理对扩散焊IN-738LC高温合金显微组织和力学性能的影响。对连接样品进行全固溶退火、部分固溶退火和时效处理3个不同的热处理。结果表明,在1120℃下焊接5 min,会导致不完全等温凝固,在焊缝处形成富Ni、Cr的硼化物共晶相。当保温时间延长到45 min时,接头中发生完全等温凝固,形成镍的先共晶固溶体γ相。等温凝固和非等温凝固样品的标准热处理能完全消除扩散影响区的硼化物相,并在等温凝固区形成γ’析出相。然而,在非等温凝固样品的接头区观察到不连续的再凝固产物。等温凝固样品经标准热处理后,剪切强度最高(约801 MPa),为基材剪切强度的99%。

Standard heat treatment effects on TLP bonded IN-738LC superalloy using BNi-9 filler:An approach to make an ideal joint

The present research is focused on the effects of standard heat treatment on the microstructure and mechanical properties of diffusion brazed IN-738LC superalloy. Three distinct heat treatment cycles of full solution annealing, partial solution annealing, and aging treatment were applied to the bonded specimens, sequentially. The results reveal that bonding at 1120 °C for 5 min leads to incomplete isothermal solidification and formation of eutectic phases including Ni- and Cr-rich borides in the joint centerline. Increasing the holding time to 45 min leads to the full isothermal solidification and formation of a nickel proeutectic solid-solution phase (γ) in the joints. The standard heat treatment of isothermally solidified and non-isothermally solidified specimensresults in the complete elimination of the boride phases in the diffusion-affected zone and also the formation of γ′ precipitates in the isothermally solidified zone. However, discontinuously re-solidified products are observed in joint district in the non-isothermally solidified sample. The highest shear strength (～801 MPa) is achieved for isothermally solidified specimen after standard heat treatment; this strength is approximately 99% that of the substrate material.