Diffusion bonding of Ti₂AlNb alloy using pure titanium (Ti) foil as an interlayer was carried out on superplastic forming and diffusion bonding special equipment by gas pressure loading method. The microstructure of Ti-Ti₂AlNb interface was observed using scanning electron microscope and energy-dispersive spectrometer while the mechanical properties of the joints were evaluated by shear test. The results show that the thickness of Ti foil interlayer has a great influence on the microstructure and shear strength of the interface diffusion region. When the thickness of the intermediate layer is thin (25 µm), Ti, aluminum (Al), and niobium (Nb) elements are fully diffused with uniform element distribution through the diffusion region. The diffusion layer region presents uniform, fine, and disordered lamellar α-Ti + β-Ti dual-phase structure with high shear strength. When the thickness of Ti foil interlayer is thick (50 µm), the distribution of Al elements is relatively uniform through the diffusion region due to its smaller radius and faster diffusion speed, and Ti and Nb elements present gradient distribution from the middle to both sides. The diffusion layer region presents a coarse and long strip shape α-Ti + β-Ti dual-phase structure in the middle part and a fine needle-like or irregular α-Ti + β-Ti dual-phase structure in both side parts, with slightly lower shear strength. Temperature has a great influence on the microstructure and mechanical properties of the diffusion bonding joints. The diffusion region presents a black α-Ti strip area in the middle part with the width of about 10 µm at lower temperature (910°C) with poorer property, due to the grain growth of the parent metal, the property is slightly poorer when the temperature is too high (960°C), and the optimal temperature is 930°C with a higher shear strength.

在超塑性成形和扩散结合专用设备上，通过气压加载法，以纯钛箔作为中间层进行Ti ₂ AlNb合金的扩散结合。Ti-Ti ₂的微观结构用扫描电子显微镜和能谱仪观察AlNb界面，并通过剪切试验评价接头的力学性能。结果表明，Ti箔中间层的厚度对界面扩散区的组织和剪切强度影响很大。当中间层的厚度薄（25μm）时，Ti，铝（Al）和铌（Nb）元素通过扩散区域以均匀的元素分布充分扩散。扩散层区域呈现出具有高剪切强度的均匀，细密和无序的层状α-Ti+β-Ti双相结构。当Ti箔夹层的厚度较厚（50 µm）时，由于其较小的半径和较快的扩散速度，Al元素在扩散区域中的分布相对均匀。Ti和Nb元素从中间到两侧呈现梯度分布。扩散层区域在中间部分呈现出粗长条形的α-Ti+β-Ti双相结构，在两侧部分呈现出细针状或不规则的α-Ti+β-Ti双相结构，剪切强度稍低。温度对扩散连接接头的组织和力学性能有很大影响。在较低温度（910℃）下，扩散区的中部呈现黑色的α-Ti带状区域，宽度约10 µm，且性能较差，由于母体金属的晶粒长大，因此当扩散区的性能稍差温度过高（960°C），最佳温度为930°C，且具有较高的剪切强度。扩散层区域在中间部分呈现出粗长条形的α-Ti+β-Ti双相结构，在两侧部分呈现出细针状或不规则的α-Ti+β-Ti双相结构，剪切强度稍低。温度对扩散连接接头的组织和力学性能有很大影响。在较低温度（910℃）下，扩散区的中部呈现黑色的α-Ti带状区域，宽度约10 µm，且性能较差，由于母体金属的晶粒长大，因此当扩散区的性能稍差温度过高（960°C），最佳温度为930°C，且具有较高的剪切强度。扩散层区域在中间部分呈现出粗长条形的α-Ti+β-Ti双相结构，在两侧部分呈现出细针状或不规则的α-Ti+β-Ti双相结构，剪切强度略低。温度对扩散连接接头的组织和力学性能有很大影响。在较低温度（910℃）下，扩散区的中部呈现黑色的α-Ti带状区域，宽度约10 µm，且性能较差，由于母体金属的晶粒长大，因此当扩散区的性能稍差温度过高（960°C），最佳温度为930°C，且具有较高的剪切强度。