热处理对Al0.5CoCrFeNi高熵合金钎焊接头组织及性能的影响

采用TiZrCuNi钎料对Al_0.5CoCrFeNi高熵合金进行钎焊连接后对其进行退火处理,研究了800 ℃下不同退火时间对钎焊接头微观组织和力学性能的影响。通过扫描电镜(SEM)、能谱仪(EDS)分析了钎焊接头微观组织及相组成,利用万能试验机测定了热处理前后试样的剪切性能。结果表明,钎焊接头的典型微观组织分为焊缝区、熔合区和热影响区3部分,焊缝区的组织主要为高熵合金相和BCC结构的FeCr基固溶体;随着退火保温时间的延长,钎焊接头焊缝区灰色相中逐步析出细小的黑色相,对接头起到了一定的弥散强化作用,微观组织更为均匀细小,钎焊接头的剪切强度由未经退火处理的554.8 MPa增加到退火12 h后的581.1 MPa。

Effect of heat treatment on microstructure and properties of Al0.5CoCrFeNi high-entropy alloy brazed joints

Al_0.5CoCrFeNi high-entropy alloy was brazed and connected with TiZrCuNi solder and then annealed, the effect of annealing time at 800 ℃ on microstructure and mechanical properties of the Al_0.5CoCrFeNi high-entropy alloy brazed joint was studied. The microstructure and phase composition of the brazed joints were analyzed by means of scanning electron microscope (SEM) and energy dispersive spectroscope (EDS). The shear strength of the specimens before and after heat treatment was measured by universal testing machine. The results show that the typical microstructure of brazed joint can be divided into weld zone, fusion zone and heat affected zone. The microstructure of weld zone mainly consists of high-entropy alloy phases and FeCr based solid solution with BCC structure. With the increase of annealing time, fine black phase gradually precipitates from the gray phase in the brazing seam, which has a certain dispersion strengthening effect on the joint, and the microstructure is finer and uniform. The shear strength of brazed joint increases from 554.8 MPa before annealing to 581.1 MPa after annealing at 800 ℃ for 12 h.