High entropy alloys have special microstructure and remarkable properties. To explore their potential engineering application in high temperature structures, the microstructure evolution of bonding interface, the elemental diffusion behavior and mechanical property of the diffusion bonded joint between AlCoCrFeNi_2.1 eutectic high entropy alloy (EHEA) and TiAl alloy were investigated. Four reaction layers (rodlike B2 phase, Al(Co, Ni)₂Ti, τ₃-Al₃NiTi₂ + TiAl, τ₃-Al₃NiTi₂ + TiAl + Ti₃Al) formed in the diffusion zone near FCC phase of EHEA, but three layers (Al(Co, Ni)₂Ti, τ₃-Al₃NiTi₂ + TiAl, τ₃-Al₃NiTi₂ + TiAl + Ti₃Al) formed near B2 phase. Al and Ni controlled the reaction diffusion of EHEA and TiAl alloy, coarsened the acicular precipitated B2 phase and turned TiAl phase into Al(Co, Ni)₂Ti and τ₃-Al₃NiTi₂ phases. All these reaction layers grew in a parabolic manner as a function of bonding temperature. Rodlike B2 phase has the lowest growth activation energy of 125.2 kJ/mol, and the growth activation energy of τ₃-Al₃NiTi₂ + TiAl layer near B2 phase is much lower than that near FCC phase. The penetration phenomenon and convex structure formed in the diffusion zone, which resulted in interlocking effect and enhanced the strength of resultant joints. The highest shear strength of 449 MPa was achieved at 950 °C. And the brittle fracture generally initiated at the interface between Al(Co, Ni)₂Ti and τ₃-Al₃NiTi₂ + TiAl layers.

高熵合金具有特殊的微观结构和卓越的性能。为了探索其在高温结构中的潜在工程应用，研究了AlCoCrFeNi _2.1共晶高熵合金（EHEA）与TiAl合金之间的键合界面的微观结构演变，元素扩散行为和扩散键合接头的力学性能。四个反应层（B2棒状相，铝（钴，镍）₂的Ti，τ ₃ -Al ₃的NiTi ₂ +的TiAl，τ ₃ -Al ₃的NiTi ₂ + TiAl金属的Ti + ₃形成在邻近的FCC相扩散区Al）的EHEA，但三层（Al（Co，Ni）₂ Ti，τ₃ -Al ₃的NiTi ₂ +的TiAl，τ ₃ -Al ₃的NiTi ₂ +的TiAl +的Ti ₃ Al）的附近形成B2相。Al和Ni控制EHEA和TiAl基合金的反应扩散，粗大的针状析出B2相和TiAl金属接通相位成的Al（钴，镍）₂ Ti和τ _3个-Al ₃的NiTi ₂相。所有这些反应层都以抛物线的方式随键合温度的增长而增长。棒状B2相具有125.2千焦/摩尔的最低生长激活能，和τ的生长活化能₃ -Al ₃的NiTi ₂B2相附近的TiAl层远低于FCC相附近的TiAl层。在扩散区中形成了渗透现象和凸结构，从而产生了互锁效应，并增强了接头的强度。在950°C下获得了449 MPa的最高剪切强度。和脆性断裂通常在铝之间的界面开始（钴，镍）_2个Ti和τ ₃ -Al ₃的NiTi ₂ + TiAl金属层。