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Rare Metals 2016年第6期35卷 456-462页

作者： Zhi-Jun Xu Yong-Zhong Zhang Ming-Kun Liu Xin-Yong Gong Center for Composites General Research Institute for Nonferrous Metals Beijing 100088 China

laser powder deposition was applied to fabricate the Ti-6.5Al-3.5Mo-1.5Zr-0.3Si （wt%）/Ti-47Al- 2Cr-2Nb-0.2W-0.15B （at%） bi-material system. The asdeposited TC11 alloy shows a basket-wave-like morphology while the as-deposited y-TiAl alloy consists of fully α2/γ lamellar microstructures. Regarding the thermal mismatch between TC11 and γ-TiAl during processing, the interface microstmcture evolution was concerned. The transformation pathway was illustrated. It is found that the content changes of Al elements and β-stabilizers Mo, Cr, and Nb are responsible for the evolution of microstructures at the interface. The fracture surfaces are located at the y-TiAl side. The bi-material shows a brittle-fracture manner, with the ultimate tensile strength of 560 MPa.

关键词： laser powder deposition TC11 titanium alloy γ-TiAl alloy Bi-material Interface

Effect of substrate preset temperature on crystal growth and microstructure formation in laser powder deposition of single-crystal superalloy

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Journal of Materials Science & Technology 2018年第11期34卷 2116-2124页

作者： Zhaoyang Liu Zi Wang College of Innovation and Entrepreneurship Southern University of Science and Technology Shenzhen Key Laboratory for Additive Manufacturing of High Performance Materials Southern University of Science and Technology State Key Laboratory of powder Metallurgy Central South University

A successful repair of single-crystal components needs to avoid the stray grain formation and achieves continuous epitaxial growth of columnar dendrites in the repaired zone. In this study, the effect of substrate preset temperature on crystal growth and microstructure formation in laser powder deposition of single-crystal superalloy was studied through an improved mathematical model and corresponding experimental approaches. The results indicated that the variation of substrate preset temperature between-30℃ and ＋210℃ changes the molten pool morphology little, but obviously affects the columnar-to-equiaxed transition conditions. The preheating of substrate facilitates the stray grain formation and enlarges the primary columnar dendrite arm spacing, while the situation for precooling of substrate is opposite. Under the specific processing conditions, the critical condition for continuous epitaxial growth is that the substrate preset temperature Tsub≤ ＋90℃. When the substrate preset temperature Tsubis below ＋90℃, the height ratio of melting depth to total height of the molten pool is larger than that of stray grain, ensuring that stray grains can be completely remelted and the continuous columnar dendrites during the multi-layer laser powder deposition process on（001） surface of single-crystal substrate can be achieved.

关键词： Single-crystal superalloy Crystal growth laser powder deposition

Optimization of Processing Parameters for laser powder deposition using Finite Element Method

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Journal of Wuhan University of Technology(Materials Science) 2010年第5期25卷 832-837页

作者：付垚 State Key Laboratory of Non-ferrous Metals and Processes General Research Institute for Non-ferrous Metals

In order to investigate the effects of powder materials and processing parameters on thermal and stress field during laser powder deposition （LPD）, a finite element model was developed with the help of ANSYS software. The finite element model was verified by the comparison between the experimental results and computed results. Then LPD processes with different powder materials and processing parameters were simulated by using the FE model. The results show that less difference of thermal conductivity and thermal expansion coefficient between powder material and substrate material produces lower residual stress; higher laser power, laser scanning speed and smaller laser beam diameter can lead higher peak temperature and higher residual stress. The research opens up a way to rational selection of the powder materials and processing parameters for ensured quality.

关键词： laser powder deposition thermal field stress field powder material processing parameters

High Power laser powder deposition Repair of AISI 4340 Steel in Aircraft Applications

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Journal of Iron and Steel Research International 2011年第S1期18卷 447-451页

作者： Mohammed Reza D Janardhana Madabhushi Brandt Milan Clark Graham School of Aerospace Mechanicaland Manufacturing EngineeringRMIT UniversityBundoora 3083VictoriaAustralia Aircraft Structural Integrity Section Directorate General Technical AirworthinessRAAFLaverton 3027VictoriaAustralia

High power laser powder deposition (LPD) has been used to investigate the potential of repairing damaged aero-grade high strength *** analysis was performed to analyze the integrity of the clad layer.A 4kW fiber laser was used to deposit two separate alloys (AISI 4340 and AISI 420 stainless steel) on an AISI 4340 steel substrate and metallurgical analysis was performed to analyze the integrity of the clad *** microcracks was observed on the clads,but porosity and high dilution was observed on most ***,microstructural analysis showed a crack and porosity free clad layer with low dilution can be achieved for some laser conditions.

关键词： laser powder deposition high strength steel fiber laser microstructure hardness