激光熔化沉积Ti60/高Nb-TiAl合金功能梯度材料的成形行为与缺陷调控OA

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.