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Enhanced high-temperature mechanical properties of laser-arc hybrid additive manufacturing of Al-Zn-Mg-Cu alloy via microstructure control

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Journal of Materials Science & Technology 2024年第2期169卷 220-234页

作者： Dehua Liu dongjiang wu Yunsong Wang Zhuo Chen Changrong Ge Qingyu Zhao Fangyong Niu Guangyi Ma State Key Laboratory of High-performance Precision Manufacturing Dalian University of TechnologyDalian 116024China

Recently,rapid and cost-effective additive manufacturing solutions for lightweight aluminum alloys with excellent high-temperature mechanical properties have been increasingly in *** this study,we combined laser-arc hybrid additive manufacturing with solution and artificial aging treatments to achieve Al-Zn-Mg-Cu alloy with favorable high-temperature strength via microstructure *** pores became the major defect in the as-deposited and heat-treated *** continuous distribution of eutectics with hard-brittle characteristics at the grain boundaries was destructed following heat ***-densityηprecipitates were uniformly dispersed in the heat-treated Al-Zn-Mg-Cu alloy,whereas appeared coarsened and dissolved at 473 K,owing to the rapid diffusion of Zn and *** average 0.2%yield strength(318±16 MPa)and ultimate tensile strength(362±20 MPa)at 473 K af-ter heat treatment were enhanced by approximately 58%and 51%,respectively,compared to those of the as-deposited *** addition,theηprecipitates contributed to lattice distortions and strain fields,which prevented dislocation motion and increased slip deformation resistance at high *** as-deposited specimen exhibited intergranular fracture at 473 K,with cracks preferring to propagate along the aggregated ***,crack propagation proceeded in the sections with more pores in the heat-treated *** approach may provide a valid option for achieving alu-minum alloys with excellent high-temperature mechanical properties.

关键词： Laser-arc hybrid additive manufacturing Al-Zn-Mg-Cu alloy High-temperature strength Heat treatment,Microstructure evolution

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Laser-assisted grinding of RB-SiC composites:Laser ablation behavior and mechanism

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Chinese Journal of Aeronautics 2024年第1期37卷 362-376页

作者： Zhigang DONG Wenchao SUN Xintong CAI Feng YANG Yan BAO Renke KANG dongjiang wu Guangyi MA Fangyong NIU Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education School of Mechanical EngineeringDalian University of TechnologyDalian 116024China

Laser ablation is an important process during Laser-Assisted Grinding(LAG)of hard and brittle *** realize controllable material removal during laser ablation of RB-SiC composites,ablation experiments under different Laser Energy Density(LAED)and LAG experiments are *** rules and mechanism of physical phase,ablation morphology and crack characteristics caused by laser irradiation are *** forces of LAG and Conventional Grinding(CG)are *** results show that ablation surface changes from slight oxidation to obvious material removal with LAED increasing,and ablation depth increases *** ablation products change from submicron SiO_(2)particles to nanoscale particles and *** LAED promotes SiC decomposition and sublimation,which leads to the increase of C *** SiC phase forms corrugated shape in recast layer and columnar shape in Heat Affected Zone(HAZ)at 56 J/mm^(2).The cold and heat cycle leads to formation of fishbone *** ablation specimen under 30 J/mm^(2),the grinding force can be reduced by a maximum of 39%and brittle damage region is *** material removal and microcrack generated will significantly reduce the hardness and improve machinability,which can promote grinding efficiency.

关键词： RB-SiC Laser Ceramic Composites Grinding

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激光-电弧复合增材制造Al-Cu合金T型结构微观组织演变与熔池流动行为分析

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航空制造技术 2024年第9期67卷 62-69,77页

作者：王儒政马广义吴胜男刘德华牛方勇吴东江中国航发控制系统研究所无锡214063 大连理工大学高性能精密制造全国重点实验室大连116024

在T型结构增材制造过程中,交叉节点处易出现冶金结合不良及重熔缺陷等问题,制约该结构性能的提升。采用激光-电弧复合增材制造技术制备了Al-Cu合金T型结构,对交叉节点处的组织形貌进行了表征,并通过数值模拟分析了节点处熔池内的温度分... 详细信息

在T型结构增材制造过程中,交叉节点处易出现冶金结合不良及重熔缺陷等问题,制约该结构性能的提升。采用激光-电弧复合增材制造技术制备了Al-Cu合金T型结构,对交叉节点处的组织形貌进行了表征,并通过数值模拟分析了节点处熔池内的温度分布以及流动特征。结果表明,在T型结构节点处能够观察到重熔作用所导致的弧形条纹特征,该区域的模拟形貌与实际结果具有良好的一致性;熔池边界处等温线分布较为密集,内部Marangoni对流导致逆时针涡流的形成,最高流速可达0.16 m/s。依据顶层晶粒形态差异,分为顶层节点重熔区(RZI)和顶层热影响区(HAZ)。其中RZI内主要为细小的树枝晶,平均晶粒尺寸相比于HAZ降低了20.8%,内部析出相主要为与α-Al基体呈非共格界面的大尺寸θ(Al_(2)Cu)相;平均显微硬度可达(98.4±6.4)HV_(0.1),相比于未重熔区最高提升约14.0%。

关键词：激光-电弧复合增材制造 Al-Cu合金 T型结构组织形貌熔池流动

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Additive Manufacturing of Ceramic Structures by Laser Engineered Net Shaping

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Chinese Journal of Mechanical Engineering 2015年第6期28卷 1117-1122页

作者： NIU Fangyong wu dongjiang MA Guangyi ZHANG Bi Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of Technology Department of Mechanical Engineering University of Connecticut

Ceramic is an important material with outstanding physical properties whereas impurities and porosities generated by traditional manufacturing methods limits its further industrial applications. In order to solve this problem, direct fabrication of Al2O3 ceramic structures is conducted by laser engineered net shaping system and pure ceramic powders. Grain refinement strengthening method by doping Zr O2 and dispersion strengthening method by doping Si C are proposed to suppress cracks in fabricating Al2O3 structure. Phase compositions, microstructures as well as mechanical properties of fabricated specimens are then analyzed. The results show that the proposed two methods are effective in suppressing cracks and structures of single-bead wall, arc and cylinder ring are successfully deposited. Stable phase of α-Al2O3 and t-Zr O2 are obtained in the fabricated specimens. Micro-hardness higher than 1700 HV are also achieved for both Al2O3 and Al2O3/Zr O2, which are resulted from fine directional crystals generated by the melting-solidification process. Results presented indicate that additive manufacturing is a very attractive technique for the production of high-performance ceramic structures in a single step.

关键词： lasers net shaping alumina ceramics additive manufacturing

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Microstructure and mechanical properties of melt-grown alumina-mullite/glass composites fabricated by directed laser deposition

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Journal of Advanced Ceramics 2022年第1期11卷 75-93页

作者： Dake ZHAO dongjiang wu Jing SHI Fangyong NIU Guangyi MA Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116024China

Melt-grown alumina-based composites are receiving increasing attention due to their potential for aerospace applications;however,the rapid preparation of high-performance components remains a ***,a novel route for 3D printing dense(<99.4%)high-performance melt-grown alumina-mullite/glass composites using directed laser deposition(DLD)is *** issues on the composites,including phase composition,microstructure formation/evolution,densification,and mechanical properties,are systematically *** toughening and strengthening mechanisms are analyzed using classical fracture mechanics,Griffith strength theory,and solid/glass interface infiltration *** is demonstrated that the composites are composed of corundum,mullite,and glass,or corundum and *** the increase of alumina content in the initial powder,corundum grains gradually evolve from near-equiaxed dendrite to columnar dendrite and cellular structures due to the weakening of constitutional undercooling and small nucleation *** microhardness and fracture toughness are the highest at 92.5 mol%alumina,with 18.39±0.38 GPa and 3.07±0.13 MPa-m1/2,*** maximum strength is 310.1±36.5 MPa at 95 mol%*** enhancement is attributed to the improved densification due to the trace silica doping and the relief of residual *** method unravels the potential of preparing dense high-performance melt-grown alumina-based composites by the DLD technology.

关键词： laser additive manufacturing alumina mullite microstructure mechanical properties

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Subsurface Damage in Scratch Testing of Potassium Dihydrogen Phosphate Crystal

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Chinese Journal of Mechanical Engineering 2009年第1期22卷 15-20页

作者： WANG Ben wu dongjiang GAO Hang KANG Renke GUO Dongming Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of Technology Dalian 116024 China

Potassium dihydrogen phosphate （KDP） is an important electro-optic crystal, often used for frequency conversion and Pockels cells in large aperture laser systems. To investigate the influence of anisotropy to the depth of subsurface damage and the profiles of cracks in subsurface of KDP crystal, an experimental study was made to obtain the form of subsurface damage produced by scratches on KDP crystal in [100], [120] and [110] crystal directions on （001） crystal plane. The results indicated that there were great differences between depth and crack shape in different directions. For many slip planes in KDP, the plastic deformation and cracks generated under pressure in the subsurface were complex. Fluctuations of subsurface damage depth at transition point were attributed to the deformation of the surface which consumed more energy when the surface deformation changed from the mixed region of brittle and plastic to the complete brittle region along the scratch. Also, the process of subsurface damage from shallow to deep, from dislocation to big crack in KDP crystal with the increase of radial force and etch pit on different crystal plane were obtained. Because crystallographic orientation and processing orientation was different, etching pits on （100） crystal plane were quadrilateral while on （110） plane and （120） plane were trapezoidal and triangular, respectively.

关键词： potassium dihydrogen phosphate (KDP) crystal scratch subsurface damage

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Investigation of melt-growth alumina/aluminum titanate composite ceramics prepared by directed energy deposition

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International Journal of Extreme Manufacturing 2021年第3期3卷 49-62页

作者： Yunfei Huang dongjiang wu Dake Zhao Fangyong Niu Guangyi Ma Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalianLiaoning Province 116024People’s Republic of China

Al_(2)O_(3)/Al_(6)Ti_(2)O_(13) composite ceramics with low thermal expansion properties are promising for the rapid preparation of large-scale and complex components by directed energy deposition-laser based(DED-LB)***,the wider application of DED-LB technology is limited due to the inadequate understanding of process *** shaping quality,microstructure,and mechanical properties of Al_(2)O_(3)/Al_(6)Ti_(2)O_(13)(6 mol%TiO_(2))composite ceramics were systematically investigated as a function of energy input in an extensive process *** this basis,the formation mechanism of solidification defects and the evolution process of microstructure were revealed,and the optimized process parameters were *** show that high energy input improves the fluidity of the molten pool and promotes the uniform distribution and full growth of constituent phases,thus,facilitating the elimination of solidification defects,such as pores and strip *** addition,the microstructure size is strongly dependent on the energy input,increasing when the energy input ***,the morphology of theα-Al_(2)O_(3) phase gradually transforms from cellular into cellular dendrite with increasing energy input due to changing solidification *** the comprehensive influence of solidification defects and microstructure size,the fracture toughness and flexural strength of Al_(2)O_(3)/Al_(6)Ti_(2)O_(13) composite ceramics present a parabolic law behavior as the energy input *** shaping quality and excellent mechanical properties are achieved at an energy input range of 0.36-0.54 W*min^(2) g^(-1) mm^(-1).Within this process window,the average microhardness,fracture toughness,and flexural strength of Al_(2)O_(3)/Al_(6)Ti_(2)O_(13) composite ceramics are up to 1640 Hv,3.87 MPa m^(1/2),and 227 MPa,*** study provides practical guidance for determining the process parameters of DED-LB of melt growth Al_(2)O_(3)/Al_(6)Ti_(2)

关键词： additive manufacturing Al_(2)O_(3) composite ceramics microstructure mechanical properties

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飞秒激光加工参数对RB-SiC表面形貌的影响

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表面技术 2024年第3期53卷 162-169页

作者：吴东江刘成杨峰牛方勇董志刚马广义康仁科大连理工大学机械工程学院辽宁大连116081

目的揭示飞秒激光加工参数对反应烧结碳化硅(Reaction-Bounded Silicon Carbide,RB-SiC)表面形貌的影响规律。方法通过改变激光能量密度和有效脉冲数,研究RB-SiC表面烧蚀槽的形貌变化规律,确定飞秒激光加工RB-SiC的去除机理。采用扫描... 详细信息

目的揭示飞秒激光加工参数对反应烧结碳化硅(Reaction-Bounded Silicon Carbide,RB-SiC)表面形貌的影响规律。方法通过改变激光能量密度和有效脉冲数,研究RB-SiC表面烧蚀槽的形貌变化规律,确定飞秒激光加工RB-SiC的去除机理。采用扫描电镜、共聚焦显微镜、X射线能谱仪和拉曼光谱仪分析RB-SiC烧蚀前后的表面形貌演变行为。结果激光能量密度在0.62~10.48 J/cm^(2)时,Si富集区域形成凹陷结构,SiC颗粒区域形成周期性结构(Laser-Induced Periodic Surface Structures,LIPSS),周期约为970 nm。随着激光能量密度的增加,凹陷结构扩大加深,表面球形纳米颗粒增多,烧蚀槽宽度呈对数增长。有效脉冲数在69~1379,Si富集区域的去除量高于SiC颗粒区域的去除量。随着有效脉冲数增加,烧蚀槽深度显著加深,凹陷结构扩展成深坑结构,飞溅至烧蚀槽外侧的纳米颗粒聚集成团簇物,由Si、SiC和非晶态SiO_(2)构成的沉积物在烧蚀槽边缘形成堆积层。结论降低激光能量密度能够减少RB-SiC表面凹陷和纳米颗粒,有助于提升烧蚀形貌的一致性。增加有效脉冲数会促进烧蚀槽底部深坑结构的产生,进而扩大Si与SiC去除量之间的差异。

关键词：飞秒激光 RB-SiC 烧蚀槽表面形貌激光能量密度有效脉冲数

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Damage mechanisms during lapping and mechanical polishing CdZnTe wafers

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Rare Metals 2010年第3期29卷 276-279页

作者： LI Yan,KANG Renke,GAO Hang,and wu dongjiang Key Laboratory for Precision and Non-Traditional Machining Technology (Ministry of Education),Dalian University of Technology,Dalian 116024,China Key Laboratory for Precision and Non-Traditional Machining Technology (Ministry of Education) Dalian University of Technology Dalian China

CdZnTe wafers were machined by lapping and mechanical polishing processes,and their surface and subsurface damages were *** surface damages are mainly induced by three-body abrasive wear and embedded abrasive wear during lapping process.A new damage type,which is induced by the indentation of embedded abrasives,is found in the *** a floss pad is used to replace the lapping plate during machining,the surface damage is mainly induced by two-body abrasive and three-body abrasive wear,and the effect of embedded abrasives on the surface is greatly ***,this new damage type nearly disappears on the subsurface.

关键词： lapping mechanical polishing wafers surface subsurface abrasive

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Cf/C-SiC烧蚀行为及激光复合超声磨削可行性研究

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表面技术 2024年第4期53卷 162-174页

作者：吴东江蔡昕彤李正董志刚马广义鲍岩康仁科牛方勇大连理工大学机械工程学院辽宁大连116024

目的揭示激光与Cf/C-SiC陶瓷基复合材料相互作用机理,分析激光能量密度对材料形性演变的影响规律。提出Cf/C-SiC陶瓷基复合材料激光复合超声磨削加工方案,探究硬脆材料多能场复合加工的可行性。方法使用不同能量密度的激光束扫描Cf/C-Si... 详细信息

目的揭示激光与Cf/C-SiC陶瓷基复合材料相互作用机理,分析激光能量密度对材料形性演变的影响规律。提出Cf/C-SiC陶瓷基复合材料激光复合超声磨削加工方案,探究硬脆材料多能场复合加工的可行性。方法使用不同能量密度的激光束扫描Cf/C-SiC陶瓷基复合材料表面,以明确材料烧蚀行为。在材料表面预制不同间距的平行纹理沟槽,进而对比传统磨削、超声辅助磨削和激光复合超声磨削的加工效果,同时研究不同扫描间距的预制沟槽对磨削效果的影响规律。结果陶瓷基复合材料(CMC)在激光作用下可呈现2种截然不同的状态,改性状态时材料以氧化等热化学变化为主,样件内出现热影响区和裂纹区。烧蚀状态时材料以热物理和热机械变化为主,样件内出现烧蚀凹坑、重铸层、热影响区和裂纹区。纤维束中界面经整体脱黏后,裂纹向下延伸并发生偏转。基体中的裂纹多起源于纤维界面处,并在扩展过程中发生偏转、分叉。激光烧蚀作用可改变材料的可加工性,有利于后续超声磨削加工。激光复合超声磨削的两方向磨削力相较传统磨削分别减小了51.4%和56.5%,同时表面粗糙度Sa可降低至4.228μm。结论激光复合超声磨削可有效降低磨削力和加工表面粗糙度,从而提高加工质量,该方法在实现硬脆材料高质量低成本加工方面具有较大的潜能。

关键词：陶瓷基复合材料激光超声磨削多能场微观形貌磨削力

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