微纳米颗粒增强TiAl复合材料拉伸行为的研究较少，且微纳米颗粒在高温下对TiAl复合材料断裂行为的影响仍不清晰，因此有必要研究微纳米Ti₂AlC颗粒增强TiAl复合材料的高温强韧化机制。本工作利用放电等离子烧结(SPS)技术原位合成微纳米Ti₂AlC颗粒增强TiAl复合材料，通过控制烧结温度，分别获得近片层、细小全片层和粗大全片层组织的Ti₂AlC/TiAl复合材料。分别在800和850℃、应变速率0.0001 s^-1条件下研究了Ti₂AlC/TiAl复合材料的高温拉伸性能及相应的强韧化机制。结果表明，微纳米尺度Ti₂AlC颗粒增强的近片层、细小全片层TiAl复合材料具有良好的强塑性，细小全片层Ti₂AlC/TiAl复合材料在850℃、0.0001 s^-1变形条件下的抗拉强度和断裂应变分别达到496 MPa和10.7%，较全片层Ti-48Al-2Nb-2Cr合金(800℃、0.0001 s^-1变形条件下抗拉强度467 MPa，断裂应变4.5%)使用温度提升50℃。Ti₂AlC/TiAl复合材料的强韧化机制主要为微纳米Ti₂AlC颗粒细化烧结组织、阻碍位错运动、促进孪晶形成、阻碍裂纹扩展，从而提高复合材料强度和塑性。

Metal matrix composites reinforced with micro-nano particles have emerged as a promising avenue for the development of advanced structural materials. Such composites can considerably enhance the strength and toughness of metals. TiAl composites with reinforced micro-nano Ti₂AlC particles exhibit excellent mechanical properties at room temperature and impressive oxidation resistance at high temperatures. However, there is limited study on the tensile behavior of micro-nano particles reinforced TiAl composites. The impact of micro-nano particles on the tensile fracture of TiAl composites at high temperatures remains largely unexplored; hence, it is crucial to investigate the high-temperature strengthening and toughening mechanisms of micro-nano Ti₂AlC particles reinforced TiAl composites. In this study, micro-nano Ti₂AlC particles reinforced TiAl composites were in situ synthesized by spark plasma sintering (SPS) at 1250-1350^oC using Ti-48Al-2Nb-2Cr prealloyed powders with addition of 0.5% graphene oxide. With increase in sintering temperature, various microstructures of Ti₂AlC/TiAl composites were observed, ranging from near fully lamellar to coarse fully lamellar. The high-temperature tensile properties of these composites with varying microstructures at 800 and 850^oC at a strain rate of 0.0001 s^-1 were systematically studied. The corresponding strengthening and toughening mechanisms were discussed based on the observed fracture morphologies. The findings revealed that the composites reinforced with micro-nano Ti₂AlC particles, especially those with near and fine fully lamellar structures, exhibited a synergy between strength and ductility at high temperatures. For instance, the fine fully lamellar Ti₂AlC/TiAl composite displayed ultimate tensile strength of 496 MPa and a fracture strain of 10.7% at 850^oC and 0.0001 s^-1. This represents a 50^oC increase in working temperature compared to that of the fully lamellar Ti-48Al-2Nb-2Cr alloy (The ultimate tensile strength and fracture strain at 800^oC and 0.0001 s^-1 were 467 MPa and 4.5%, respectively). The enhanced high-temperature properties of the Ti₂AlC/TiAl composites were primarily attributed to the micro-nano Ti₂AlC particles, which refined the lamellar colonies and hindered dislocation movement and crack propagation.