航空材料学报2026，Vol.46Issue(1)：51-59,9.DOI:10.11868/j.issn.1005-5053.2025.000121
整体高温辅助激光定向能量沉积TiAl4822合金开裂抑制机理及组织性能研究
Suppression of cracking and microstructure-property investigation of TiAl4822 alloy by laser directed energy deposition with integral high-temperature assistance
摘要
Abstract
The TiAl4822(Ti-48Al-2Cr-2Nb)alloy,renowned for its exceptional high-temperature mechanical properties and low density,stands out as a highly promising candidate for critical aerospace components.However,its high chemical reactivity and inherent room-temperature brittleness pose significant challenges to the conventional manufacturing of large and complex geometries.Laser directed energy deposition(LDED),characterized by its high fabrication efficiency and remarkable process flexibility,has emerged as a crucial approach for preparing TiAl4822 alloy components.Nevertheless,the rapid melting-solidification cycle during LDED induces a substantial temperature gradient and residual stress,which results in component cracking.Currently,there is no well-established method to completely prevent crack formation.In this study,a dense and crack-free thin-walled TiAl4822 alloy component with dimensions of 30 mm×25 mm×6 mm is successfully fabricated using the whole high-temperature-assisted LDED technique.An investigation is conducted on their macro-morphology,microstructure,porosity,and microhardness.The results reveal that the thin-walled TiAl4822 alloy specimen prepared by LDED at room temperature is prone to brittle fracture primarily through cleavage,and its microstructure mainly comprises fine equiaxed grains.After implementing whole high-temperature assistance at an integral temperature of 800℃,the grains in the deposited layer transform from bottom to top into inclined columnar grains.The porosity is significantly reduced from 0.05%to 0.008%,accompanied by a more uniform pore-size distribution,and no macroscopic cracks are observed on the surface.Concurrently,the microhardness decreases from 390.46HV0.2 to 354.94HV0.2,which can be attributed to grain coarsening,a decrease in grain-boundary density,and precipitate evolution under high-temperature conditions.Overall,the integral high-temperature-assisted LDED effectively inhibits crack initiation and the formation of large pores while homogenizing the microstructure,providing a novel pathway for high-density,high-performance TiAl4822 preparing.关键词
激光定向能量沉积/TiAl4822合金/裂纹/显微组织/显微硬度Key words
laser directed energy deposition/TiAl4822 alloy/crack/microstructure/microhardness分类
航空航天引用本文复制引用
牛方勇,祝明春,成浩然,于学鑫,高佳丽..整体高温辅助激光定向能量沉积TiAl4822合金开裂抑制机理及组织性能研究[J].航空材料学报,2026,46(1):51-59,9.基金项目
国家自然科学基金项目(52375312) （52375312）
大连理工大学精密/特种加工及微制造技术教育部重点实验室(B类)开放课题基金资助项目(B202305) （B类）
