Microstructure and mechanical properties of the brazed region in the AlCoCrFeNi high-entropy alloy and FGH98 superalloy joint
Microstructure and mechanical properties of the brazed region in the AlCoCrFeNi high-entropy alloy and FGH98 superalloy joint
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DOI：
10.1016/j.msea.2020.140714
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发表时间：
2021-02
期刊：
影响因子：
6.4
通讯作者：
Shiwei Li;Jinglong Li;Junmiao Shi;Yajie Du;Yu-Chang Peng;F. Jin;J. Xiong;Fu-Sheng Zhang
中科院分区：
文献类型：
--
作者：
Shiwei Li;Jinglong Li;Junmiao Shi;Yajie Du;Yu-Chang Peng;F. Jin;J. Xiong;Fu-Sheng Zhang
采用BNi-2钎料实现了Al0.3CoCrFeNi高熵合金与FGH 98高温合金的钎焊。分析了Al0.3CoCrFeNi/FGH 98接头的显微组织，并对不同钎焊温度下接头的力学性能进行了评价。在钎焊过程中，硼从钎料中扩散到Al 0. 3CoCrFeNi基体中，并主要与Cr反应生成富Cr的硼化物，其结构为Cr 5 B3。最终，反应区由富Cr硼化物和富Ni HEA基体组成，并具有[0 1 1]富Ni HEA//[2 4 0]富Cr硼化物和（2 0 0）富Ni HEA//（0 0 2）富Cr硼化物的共格关系。FGH 98基体的溶解导致焊缝中出现岛状（γ + γ）相。随着钎焊温度的升高，空洞和硼化物消失，最终钎缝转变为均匀的Ni（s.s）。此外，当钎焊温度达到1090和1110 °C时，晶间富Cr硼化物的体积显著增加，靠近钎焊缝的FGH 98基体中碳化物（或硼化物）的析出呈弥散状。当钎焊温度为1070 °C，钎焊时间为10 min时，接头的剪切强度最高，为454 MPa，在剪切过程中接头发生了韧性断裂。
In this study, brazing of Al0.3CoCrFeNi high-entropy alloy to FGH98 superalloy was achieved using a BNi-2 filler metal. The microstructure of the Al0.3CoCrFeNi/FGH98 joint was examined, and mechanical properties of the joints brazed at different brazing temperatures were evaluated. During the brazing process, boron diffused from the filler alloy into the Al0.3CoCrFeNi substrate, and mainly reacted with Cr to form the Cr-rich boride exhibiting Cr5B3structure. Eventually, the reaction zone was composed of a Cr-rich boride and Ni-rich HEA matrix with a coherent relationship of [0 1 1]Ni-rich HEA//[2 4 0]Cr-rich borideand (2 0 0)Ni-rich HEA//(0 0 2)Cr-rich boride. The dissolution of the FGH98 substrate induced the island-like (γ + γʹ) phase in the brazing seam. With the brazing temperature increasing, the voids and borides disappeared, and finally the brazing seam transformed into homogeneous Ni(s.s). Moreover, when the brazing temperature reached 1090 and 1110 °C, the volume of intergranular Cr-rich borides increased significantly, and the precipitation of carbides (or borides) in the FGH98 substrate adjacent to the brazing seam was dispersive. The optimum shear strength of 454 MPa was obtained when the brazing was carried out at 1070 °C for 10 min, and ductile fractures occurred in the joint during the shear test.