This paper conducts diffusion bonding of Ti₂AlNb based alloy, in which a novel refractory high-entropy alloy (Ti₄₀Nb₃₀Hf₁₅Al₁₅; RHEA) was used as the interlayer. The RHEA interlayer is designed to eliminate bond line and restrain the aggregation of orthorhombic (O) phase at bonding interface. The microstructures of joints were investigated by scanning and transmission electron microscopy (SEM and TEM, respectively). Defect-free joints were obtained when bonding was performed in the temperature range of 950–1000 °C at 30 MPa for 2 h. The joint microstructure was mainly composed of a disordered bcc-type solid solution and nanosized basketweave ordered O phase. According to the TEM results, the matrix was rich in Hf, which strengthened the matrix by solid solution strengthening. The tiny O phase retained a specific coherent relationship with the bcc matrix, (001)_O// $\left(01\bar{1}\right)$_bcc and $\left[0\bar{1}1\right]$_O// $\left[\bar{1}11\right]$_bcc, which strengthened the bonding interface by precipitation strengthening. This multiphase coupling interface indicated reliable metallurgical bonding and guaranteed excellent joint performance. The mechanical properties of the joints were evaluated using nanoindentation and shear tests. The microhardness and Young's modulus were distributed evenly without any noticeable fluctuation and ranged from 5.01 to 5.52 GPa and 103.97–117.22 GPa, respectively, illustrating the suitable property matching between the high-entropy interlayer and Ti₂AlNb. The maximum shear strength of the joint was 463 MPa with bonding at 970 °C and 30 MPa for 2 h. The main crack was significantly deflected into the parent materials, rather than propagating along the interface, which further demonstrated that the bonding face had higher strength than the base metals. The precipitation mechanism of the nanoscale O phase was revealed through transmission Kikuchi diffraction–electron backscatter diffraction (TKD-EBSD). The O phase variants formed with equal probability could lead to a basketweave morphology. The successful bonding of Ti₂AlNb using RHEA as the interlayer provides a new interlayer system to bond Ti-based intermetallic compounds.

本文对Ti ₂ AlNb 基合金进行扩散结合，其中一种新型难熔高熵合金（Ti ₄₀ Nb ₃₀ Hf ₁₅ Al ₁₅; RHEA)用作中间层。RHEA中间层旨在消除粘合线并抑制正交（O）相在粘合界面处的聚集。通过扫描和透射电子显微镜（分别为SEM和TEM）研究接头的微观结构。当在 950-1000 °C 的温度范围内以 30 MPa 进行 2 小时的粘合时，可以获得无缺陷的接头。接头显微结构主要由无序的体心立方固溶体和纳米级的篮状有序O相组成。根据TEM结果，基体富含Hf，通过固溶强化强化了基体。微小的 O 相与 bcc 矩阵保持特定的相干关系， (001) _O //$\left(01\bar{1}\right)$_密件抄送和$\left[0\bar{1}1\right]$_哦//$\left[\bar{1}11\right]$_bcc，通过沉淀强化强化了键合界面。这种多相耦合界面表明了可靠的冶金结合并保证了出色的接头性能。使用纳米压痕和剪切试验评估接头的机械性能。显微硬度和杨氏模量分布均匀，无明显波动，分别在 5.01 至 5.52 GPa 和 103.97 至 117.22 GPa 之间，说明高熵中间层与 Ti _{2之间的性能匹配合适}铌酸铝。接头的最大剪切强度为 463 MPa，在 970 °C 和 30 MPa 下粘合 2 小时。主裂纹明显偏向母材，而不是沿界面扩展，这进一步证明了结合面的强度高于母材。通过透射菊池衍射-电子背散射衍射（TKD-EBSD）揭示了纳米级O相的沉淀机制。以相等概率形成的 O 相变体可能导致篮编织形态。使用 RHEA 作为中间层成功键合 Ti ₂ AlNb 为键合 Ti 基金属间化合物提供了一种新的中间层系统。