(1. 湖南科技大學高功效輕合金構件成形技術及耐損傷性能評價湖南省工程研究中心，湘潭 411201；
2. 中南大學輕質高強結構材料國家級重點實驗室，長沙 410083；
3. 湖南云箭集團有限公司，長沙 410100)
摘 要: 利用激光粉末沉積技術制備輕質Ti/Al密度梯度材料，采用掃描電子顯微鏡、電子探針顯微分析儀、能譜儀、顯微硬度測試儀等，分析了梯度材料的組織結構特征，研究了激光粉末沉積輕質Ti/Al密度梯度材料的裂紋形成機理及其自愈合行為。結果表明：輕質Ti/Al密度梯度材料的微觀組織呈現(xiàn)漸變特征，相結構轉變呈現(xiàn)Ti→Ti3Al→TiAl+Ti5Si3→TiAl3+TiAl+Ti5Si3+Al→Ti Al3+Al的規(guī)律變化；各梯度層(Ⅰ~Ⅴ)的平均硬度分別為370.9 HV0.1、619.4 HV0.1、567.7 HV0.1、459.5 HV0.1和213.8 HV0.1。梯度層中觀察到裂縫存在，該裂紋在界面或缺陷(孔洞等)處萌生，在激光粉末沉積輕質Ti/Al密度梯度材料過程中，后續(xù)形成的熔池內金屬溶液對裂紋具有填充作用，從結構上完成自修復，使裂縫得以愈合，可有效阻止裂紋進一步擴展。
關鍵字: 增材制造；激光粉末沉積；梯度材料；裂紋；自愈合行為；組織結構演變
（1. Hunan Engineering Research Center of Forming Technology and
Damage Resistance Evaluation for High Efficiency Light Alloy Components,Hunan
University of Science and Technology, Xiangtan 411201, China;
2. National Key Laboratory of Science and
Technology for High-strength Structural Materials,Central South University,
Changsha 410083, China;
3. Hunan Vanguard Group Co. Ltd., Changsha 410100,
China）
Abstract:A novel lightweight Ti/Al density gradient material was fabricated successfully using the laser powder deposition technology. The microstructures of gradient materials were characterized by the scanning electron microscope, electron probe microanalyzer, energy spectrometer and microhardness tester. The crack formation mechanism and self-healing behavior were studied. The results show that the microstructure of lightweight Ti/Al density gradient material shows gradual change, and the phase evolution shows the regular change of Ti→Ti3Al→TiAl+Ti5Si3→TiAl3+TiAl+Ti5Si3+Al→TiAl3+Al. The average hardness of each gradient layer (Ⅰ-Ⅴ) are 370.9 HV0.1, 619.4 HV0.1, 567.7 HV0.1, 459.5 HV0.1 and 213.8 HV0.1, respectively. The cracks are observed in the gradient layer, which initiate at the interface or defects (holes, etc.). In the process of laser powder deposition of light Ti/Al density gradient materials, the subsequent metal solution in the molten pool can fill the cracks, complete self repair structurally, make the cracks heal and effectively prevent the further expansion of cracks.
Key words: additive manufacturing; laser powder deposition; gradient material; crack; self-healing behavior; microstructure evolution
