【摘要】 为满足航空发动机高温部件对轻量化与性能梯度化的迫切需求，本文采用激光熔化沉积(LMD)技术，系统研究了工艺参数对Ti60合金、高Nb-TiAl合金及其不同比例混合合金薄壁件成形质量的影响，并探索Ti/TiAl功能梯度材料(FGM)稳定成形的可行路径。结果表明，Ti60合金通过工艺优化可获得细小均匀且无明显缺陷的网篮组织；高Nb-TiAl合金沉积过程中存在元素偏析，高能量输入易诱发气孔，而在较低功率下通过300℃预热及连续沉积可有效抑制裂纹，获得细小全片层组织。混合合金在合理能量输入下可实现无裂纹、无气孔成形。直接过渡Ti/TiAl复合材料易在熔合线附近开裂，而通过逐级调整熔宽参数(Ti60、过渡区A、过渡区B及TiAl的熔宽分别为7.0、6.5、6.0、5.5 mm)构建功能梯度结构，可实现良好的组织与变形协调，功能梯度材料内部未观察到明显裂纹缺陷。双梯度结构(Ti/A/B/TiAl)由于引入更多成分过渡台阶，能进一步缓解界面处应力集中与硬度突变，表现出比单梯度结构更好的协调性和成形稳定性。更多还原

【Abstract】 To address the urgent demand for lightweight designs and performance gradations in high-temperature aeroengine components, this study employed laser melting deposition(LMD) to systematically investigate the influence of processing parameters on the forming quality of thin-walled components fabricated from Ti60 alloys, high-Nb-TiAl alloys, and their blended compositions and to explore feasible strategies for fabricating crack-free Ti/TiAl functionally graded materials(FGMs). The results demonstrate that with optimized parameters, Ti60 alloy develops a fine and uniform basket-weave microstructure without significant defects. For high Nb-TiAl alloys, elemental segregation occurs during deposition, and excessive energy input readily induces porosity. By preheating at 300 ℃ and adopting a continuous deposition strategy,cracking is effectively suppressed, resulting in a refined fully lamellar microstructure. Mixed alloys can be deposited without cracks or pores under appropriate energy input. While direct Ti/TiAl transition joints are prone to cracking near the fusion line,a functionally graded structure fabricated through stepwise adjustment of the melt pool width(7.0 mm for Ti60, 6.5 mm for transition zone A, 6.0 mm for transition zone B, and 5.5 mm for TiAl) achieves good microstructural compatibility and deformation coordination, with no noticeable cracks observed within the graded region. Compared with single-gradient configurations, the double-gradient structure(Ti/A/B/TiAl), which introduces additional compositional transition steps, further mitigates interfacial stress concentration and abrupt changes in hardness, resulting in superior coordination and forming stability.更多还原