Microstructural evolution and micro-mechanical properties of non-isothermal solidified zone in TLP bonded Ni-based superalloy joints

作者：Yi Zhang, Yiming Zhong, Yongxin Cheng, Neng He, Lianlong He, Zhenhuan Gao, Xiufang Gong, Chunlin Chen, Hengqiang Ye · 发表于：Journal of Material Science and Technology · 年份：2023 · DOI：10.1016/j.jmst.2023.11.006 · 被引用次数：21 · 研究领域：High Temperature Alloys and Creep、Intermetallics and Advanced Alloy Properties、Aluminum Alloy Microstructure Properties

Transient liquid phase (TLP) bonding is a promising process for the joining and repairing of nickel-base superalloys. One of the most important parameters in TLP bonding is the bonding time required for sufficient isothermal solidification which prevents the formation of undesirable precipitated phases. In the present work, the effect of bonding time on the microstructure, type, and evolution of precipitates in the non-isothermal solidified zone (NSZ) and their effect on micro-mechanical properties were systematically investigated using multi-scale tests in TLP bonded Mar-M247 superalloy joints with Ni-15.2Cr-3.74B interlayer at 1230 ℃. For a bonding time of 5 min, dual-phase M 23 (C, B) 6 - γ/γ’ (where M is a mixture of Hf, Ta, Cr, and Ni) with eutectic configuration was formed in NSZ. With the increase in bonding time, the evolution of NSZ microstructure can be summed up as eutectic M 23 (C, B) 6 - γ/γ’, semi-striping dual-phase M 23 (C, B) 6 - γ/γ’, discontinuously striping M 23 (C, B) 6 - γ/γ’, followed by the disintegration of NSZ. As the NSZ counterpart, the isothermal solidified zone (ISZ) is mainly composed of γ/γ’. Accompanied by the dissolution of M 23 (C, B) 6 in the centerline, the proportion of the ISZ increases greatly until the joints are completely occupied by ISZ. Finally, a bamboo-like structure with domain size of ∼100 μm was formed in the joint centerline, along with γ’ reorganized themselves all into cubic shapes and distributed homogeneously. Mechanical ...