为满足目前高温原位中子衍射实验对耐高温且无中子衍射峰的环境结构材料的迫切需求，本工作开发出一种高熔点的TiTaAl零相干散射合金(Ti-27.24Ta-9.08Al，原子分数，%)，为评估其在长期服役和异常工况下(气体泄露)的高温抗氧化性能，探究了TiTaAl合金在高温条件下的氧化机制。结果表明，在1000 ℃下，该合金的氧化动力学行为呈现出明显的两阶段特征。在初期氧化阶段(< 10 h)，氧化动力学遵循抛物线速率定律，氧化层主要分为三层：外层为TiO₂、中间层为Al₂O₃、内层为Ta₂O₅，三层结构形成致密的保护膜，有效阻碍了O向内扩散。然而，随着暴露时间延长(>10 h)，氧化动力学转变为线性规律， 氧化层出现孔洞微裂纹等缺陷，为氧的快速渗透提供了通道，从而显著加快了氧化速率。

Neutrons possess characteristics such as deep penetration, isotope sensitivity, and a magnetic moment, which make them pivotal in fields including engineering materials, polymers, energy materials, and condensed matter physics. Their strong penetrating ability enables applications in complex external-field sample environments, providing an ideal platform for investigating structure–property relationships of materials under extreme conditions. However, background signals originating from sample-environment equipment can interfere with the precise analysis of neutron diffraction data. Null-matrix alloys, characterized by the absence of neutron diffraction peaks, are ideal structural materials for neutron scattering experimental sample environments, as they do not interfere with diffraction signals from the target sample and thus enable accurate structural characterization during in situ experiments. A key challenge in current high-temperature in situ neutron diffraction experiments is the lack of null-matrix materials with sufficient high-temperature resistance. Conventional Ti–Zr alloys have melting points of only about 1550 °C, undergo softening and recrystallization above 750 °C that lead to interfering diffraction peaks, and present poor processing safety. Vanadium and its alloys, meanwhile, are prone to oxidation above 675 °C and suffer significant embrittlement beyond 1200 °C, which limits their reusability. These deficiencies severely constrain the development of high-temperature in situ neutron diffraction experiments. To address these limitations, a high-melting-point, oxidation-resistant Ti–Ta–Al null-matrix alloy (Ti–27.24Ta–9.08Al, atomic fraction, %) has been developed to meet the requirements of high-temperature in situ neutron diffraction experiments. To further evaluate its oxidation resistance, a systematic investigation of its high-temperature oxidation behavior in air was conducted. The results reveal a distinct two-stage oxidation kinetics behavior at 1000 °C. During the initial oxidation stage (< 10 h), the oxidation kinetics follow a parabolic rate law, and the oxide layer is mainly composed of TiO₂, Al₂O₃, and Ta₂O₅, forming a dense barrier that impedes inward oxygen diffusion. With prolonged exposure (> 10 h), the oxidation behavior transitions to linear kinetics, driven by abnormal coarsening of TiO₂ grains. The resulting structural discontinuities facilitate rapid oxygen penetration along grain boundaries, thereby accelerating the oxidation rate.