铝锂合金超塑成形/扩散连接技术研究进展

Research progress of Al-Li alloy superplastic forming/diffusion bonding technique

轻量化材料与结构是现代航空航天工业的发展方向。铝锂合金密度小,比强度、比弹性模量高,是理想的航空航天材料。采用超塑成形/扩散连接工艺成形的空心夹层结构零件具有整体性好、设计自由度大、成形精度高、无残余应力等优点,而且能够大幅减重、降低成本,广泛应用于航空航天领域。针对航空航天领域对新一代复杂多层结构件整体化和轻量化的迫切需求,回顾了国内外铝锂合金的发展历程,介绍了国内外铝锂合金超塑成形、扩散连接以及超塑成形/扩散连接组合技术的发展现状及其在航空航天领域的应用,指出铝锂合金表面致密稳定氧化膜是阻碍其扩散连接接头质量提升的瓶颈问题,讨论去除铝锂合金表面的氧化层以及防止新的氧化层再生的相关工艺与机理,最后展望了铝锂合金超塑成形/扩散连接技术在航空航天领域的应用前景以及未来研究方向。

Lightweight materials and structures are the development direction of the modern aerospace industry.Aluminum-lithium alloy is a kind of ideal aerospace material due to low density,high specific strength and high specific elastic modulus.The hollow sandwich structure parts formed by the superplastic forming/diffusion bonding process have the advantages of good integrity,large design freedom,high forming accuracy,no residual stress.Furthermore,the weight and cost can be significantly reduced and they are widely used in the aerospace field.In response to the urgent need for the integration and lightweight of the new generation of complex multi-layer structural parts in the aerospace industry,the development history of aluminum-lithium alloys at home and abroad are reviewed.The state of the art in aluminum-lithium alloy superplastic forming,diffusion bonding and superplastic forming/diffusion bonding combined processes and their applications in the aerospace field are introduced.The dense and stable oxidation film on the surface of aluminum-lithium alloy hinders the quality improvement of its diffusion bonding joint and becomes the bottleneck problem.The related technology and mechanism of removing the oxide layer on the surface of the aluminum-lithium alloy and preventing the regeneration of the new oxide layer are analyzed.Finally,the application prospect of the aluminum-lithium alloy superplastic forming/diffusion bonding technology in the aerospace field and the research topics in the future are forecasted.