Effect of heat treatments on the microstructure and mechanical properties of Ti2AlNb intermetallic fabricated by selective laser melting
Effect of heat treatments on the microstructure and mechanical properties of Ti2AlNb intermetallic fabricated by selective laser melting
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DOI：
10.1016/j.msea.2021.141352
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发表时间：
2021-06
期刊：
影响因子：
6.4
通讯作者：
Y. Zhou;D. W. Wang;L. Song;A. Mukhtar;D. Huang;C. Yang;Ming Yan
中科院分区：
文献类型：
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作者：
Y. Zhou;D. W. Wang;L. Song;A. Mukhtar;D. Huang;C. Yang;Ming Yan
Ti2AlNb （Ti-22Al-25Nb at）从减轻重量的角度来看，金属间化合物对航空航天工业至关重要，并带来了取代某些镍基高温合金的可能性。尽管元素Al(从其原始成分22.8 at蒸发。%至18.5%。%)，选择性激光熔化（SLM）技术在制造具有优异室温性能的Ti2AlNb金属间化合物方面具有明显的优势。充分了解相应的热处理机理是在高温下充分利用slm制备的Ti2AlNb的关键。本研究旨在阐明slm制备和热处理Ti2AlNb的微观结构与力学倾向之间的关系，最终获得良好的高温力学性能。为此，对其进行了一系列热处理，并采用先进的表征技术对其显微组织、力学性能进行了系统的研究。结果表明，室温和高温下的力学性能与热处理方式有关。在950℃固溶处理后，在700℃时效处理，由于形成针状O相、α2相和晶界α2相，样品表现出良好的室温和高温强度。但其延展性较差。830℃时效使强度降低，但由于棒状O相的出现和B2/β相比例的增加，塑性显著提高。该合金具有良好的强度和塑性（611 MPa, 10.0%），在650℃时具有较高的热稳定性。进一步证明，热处理后的Ti2AlNb具有良好的比强度，甚至高于铸态Inconel 718高温合金。因此，开发的合金在需要高温性能和减轻重量的行业中具有很高的潜力。
Ti2AlNb (Ti–22Al–25Nb at.%, nominal composition) intermetallic is essential to aerospace industry from a weight reduction perspective, and brings a possibility of replacing some Ni-based superalloys. Despite evaporation of element Al (from its original composition 22.8 at.% to 18.5 at.%), selective laser melting (SLM) technology offers distinct advantages in fabricating Ti2AlNb intermetallic with superior room-temperature properties. A full understanding of corresponding heat treatment mechanism is the key to utilize well the SLM-prepared Ti2AlNb at high temperatures. This study aims to clarify the relationship between the microstructure and mechanical propensities of SLM-prepared then heat-treated Ti2AlNb, to ultimately achieve promising mechanical performances at high temperatures. For this research purpose, a series of heat treatments were conducted, and the corresponding microstructures, mechanical properties were systematic studied by advanced characterization techniques. Results show that the mechanical properties at both room and high temperatures depend on heat treatment adopted. The samples solution-treated at 950 °C and then aged at 700 °C show promising room and high temperature strengths due to the formation of acicular O, α2and grain boundary α2phases. However, their ductility was poor. Aging at 830 °C reduces the strength, but significantly improves the ductility due to the appearance of rodlike O phase and the increase of B2/β phase proportion. The alloy possesses promising strength and ductility (611 MPa, 10.0%) and high thermal stability at 650 °C. It is further demonstrated that the heat-treated Ti2AlNb possesses promising specific strength, even higher than that of as-cast Inconel 718 superalloy. The developed alloy, therefore, has a high potential for the industries requiring high-temperature performance and weight reduction.