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- 2018
- tumor imaging
- conductivity
- MRI
- EPT
- Electrical properties tomography
- Optoelectronic Information Science and Engineering
- Ghent University
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Microstructure and properties of high strength and high conductivity Cu-Cr alloy components fabricated by high power selective laser melting
摘要： Although different kinds of metal materials have been built in the past years, it is difficult to fabricate the components of copper alloys with high strength and high conductivity due to their high reflectivity and thermal conductivity. In this paper, Cu-Cr alloy with high strength and high conductivity was successfully manufactured by high laser power selective laser melting. The microstructure, mechanical properties and conductivity were studied and compared before and after the heat treatment. The microstructure of the as-built sample was columnar grains with very fine cellular sub-structures and precipitates of Cr and Cr2O3. After heat treatment, the Cr particles precipitated from Cu matrix, resulting in simultaneous increase in strength and conductivity. The ultimate tensile strength of 468 MPa, yield strength of 377.33 MPa, and electrical conductivity of 98.31% IACS were achieved, which is even better than the samples fabricated by rolling with post heat treatment.
关键词： Cu-Cr alloy,Electronic conductivity,Laser processing,Microstructure,Mechanical properties
更新于2025-11-28 14:24:20
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Effects of Substrate Preheating Temperatures on the Microstructure, Properties, and Residual Stress of 12CrNi2 Prepared by Laser Cladding Deposition Technique
摘要： The 12CrNi2 alloy steel powder studied in the present paper is mainly used to manufacture camshafts for nuclear power emergency diesel engines. Laser cladding deposition is of great signi?cance for the manufacture of nuclear power emergency diesel camshafts, which has the advantages of reducing material cost and shortening the manufacturing cycle. However, due to the extremely uneven heating of the components during the deposition process, a complex residual stress ?eld occurs, resulting in crack defects and residual deformation of the components. In the present paper, 12CrNi2 bulk specimens were prepared on the Q460E high-strength structural steel substrate at different preheating temperatures by laser cladding deposition technique, and a ?nite element residual stress analysis model was established to investigate the effects of different preheating temperatures on the microstructure, properties, and residual stress of the specimens. The results of the experiments and ?nite element simulations show that with the increase of preheating temperature, the content of martensite/bainite in the deposited layer decreases, and the ferrite content increases. The proper preheating temperature (150 ?C) has good mechanical properties. The residual stress on the surface of each specimen decreases with the increase of the preheating temperature. The longitudinal stress is greater at the rear-end deposition part, and the lateral residual stress is greater on both sides along the scanning direction.
关键词： substrate preheating,12CrNi2 alloy steel powder,residual stress,laser cladding deposition,microstructure and properties
更新于2025-11-28 14:24:20
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Analysis of properties laser welded RAK 40/70 steel sheets
摘要： Both, the ecological production and operation of vehicles demand using such materials for deformation zones’ structural parts, which show some specific properties and use innovative technologies to process them. Specific requirements for functionality (strength, stiffness, deformation work, fatigue properties) are closely linked to processability (formability). In the paper are presented results for multiphase TRIP steel RAK40/70 when welded by pulse solid-state fiber laser YLS-5000. Based on microstructure analysis in the fusion zone and heat affected zone the welding parameters were optimised. The influence of laser welding on the strength and deformation properties was verified by characteristics of strength, stiffness and deformation work, as they were calculated from mechanical properties measured by tensile test and three-point bending test. The knowledge gathered in the field of laser welding influence on the strength and deformation properties of multiphase TRIP steel RAK40/70 should help designers when design the lightweight structural parts of the car body.
关键词： mechanical properties,TRIP steel,RAK 40/70,microstructure,laser welding
更新于2025-11-28 14:24:20
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Influence of Technological Parameters of Direct Laser Deposition Process on the Structure and Properties of Deposited Products from Alloy Ti-6Al-4V
摘要： The technology of direct laser deposition is the most promising for using in various industries. One of the most interesting areas for using this technology is an aviation industry. Due to their unique properties, titanium alloys are widely used in the aircraft industry for gas turbine engine components. In this paper, the effect of DLD process parameters on defect formation and structure is considered. The influence of energy density on the mechanical properties of parts is determined.
关键词： Direct Laser Deposition,additive manufacturing,mechanical properties,Titanium alloys
更新于2025-11-28 14:24:20
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Laser welding of AZ31B magnesium alloy with beam oscillation
摘要： Circular beam oscillation was introduced to laser welding of 2 mm-thick AZ31 magnesium alloy. The appearance, microstructure and tensile properties of the welds were investigated. It was found that the low frequency about 50 Hz and the small radius about 0.5 mm are more beneficial to improve the weld appearance, under the given parameters of laser power 2 kW, welding speed 2 m/min and beam oscillating diameter 0.35 mm. The undercut defect and even the totally collapse of the weld appear when employing the frequency higher than 75 Hz or the radius larger than 1.5 mm. The microstructure evolution mainly reflects in the variation of the proportions of the equiaxed zone (PEZ) and the average grain size (SG). The PEZ decreases from 85% to 42% with the beam oscillating frequency increasing from 25 Hz to 100 Hz, while the SG reaches the maximum of 37.5 μm at 75 Hz. The PEZ decreases and the SG increases with the increase of beam oscillating radius. The results showed that the tensile strength and elongation are closely related to the PEZ, the SG and the twins. According to the experimental results, the relationship of oscillating parameters, microstructure, and tensile properties was established.
关键词： Laser oscillating welding,Magnesium alloy,Microstructure,Tensile properties
更新于2025-11-28 14:24:20
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Microstructural Characteristics of Laser Metal Deposited Magnesium Alloy AZ31
摘要： Up to now, only a limited amount of metallic materials is investigated for laser additive manufacturing (LAM). However, the demand to widen the application possibilities by enlarging the range of materials for LAM is growing fast. By now, titanium and aluminium alloys are in the focus of research. In contrast, magnesium alloys are rarely used in the field of additive manufacturing, although they possess a low density in combination with a high specific strength. Currently, magnesium structures are mainly produced by casting but during the last years, the use of wrought alloys also increased. A reason for the rare use of magnesium alloys for LAM technologies might be the high flammability of magnesium powders. This difficulty can be avoided by using magnesium wire for laser metal deposition (LMD). In the present study, the microstructural characteristics of a LMD processed AZ31 magnesium alloy are investigated. For this purpose, optical microscopy and scanning electron microscopy were used. With the help of EDX and EBSD analysis, a change of the chemical composition and micro texture with structure height was identified. The relationship of microstructure and local mechanical properties was investigated with the help of Vickers micro hardness testing. Based on the obtained results it can be concluded that the microstructural characteristics of laser additive manufactured magnesium alloys differ from those of titanium and aluminium alloys. Thus, a wider application spectrum of LMD and magnesium alloys can be opened up.
关键词： laser metal deposition,local mechanical properties,microstructure,magnesium alloy,wire,microtexture
更新于2025-11-28 14:24:20
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Autogenous fiber laser welding of 70/30 Cu-Ni alloy plates
摘要： Cupronickel alloys such as 70/30 Cu-Ni have excellent resistance to sea water corrosion and anti-fouling properties, and thus have been widely used for naval and offshore applications. Traditionally, arc welding and brazing processes have been used to weld such materials. In contrast, laser beam welding is a promising technology due to its high productivity, good process flexibility and reliability, and good welding integrity. In the present work, a high power fiber laser system is used to weld 5-mm thick 70/30 Cu-Ni alloy plates in a configuration of butt joints. Then, the laser welded joints are evaluated in terms of microstructures, defects, and mechanical properties (hardness, face and root bend, and tensile) in accordance with the applicable International Organization for Standardization and Defence Standard specifications.
关键词： Tensile Properties,Microstructure,Butt Joint,Cupronickel Alloy,Bend testing,Laser Welding
更新于2025-11-28 14:24:20
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Influence of Al-Si coating on microstructure and mechanical properties of fiber laser welded 22MnB5 steel
摘要： Fiber laser welding of as-received 22MnB5 steel with Al-10wt.%Si coating in butt configuration was performed. The influence of Al-Si coating on microstructure transformation and mechanical properties including tensile tests, fatigue tests and Erichsen cupping tests was investigated. Ferrite with Al enrichment (1.37 wt%) was found in the fusion zone (FZ) of coated welded joints with 15% area proportion, while nearly entire martensite structure composed the FZ in the case of de-coated joint. The strain localization was more likely to accumulate at the martensite/martensite interface rather than the ferrite/martensite interface due to the higher kernel average misorientation (KAM) values. Microhardness of the FZ in coated welded joints dropped by 50HV compared with that of de-coated welded joints. However, tensile properties were not affected since failure occurred at base metal (BM). Fatigue samples of coated welded joints showed better performance than the de-coated ones, suggesting that the ferrite in the FZ had positive effect on fatigue lives under cycling load conditions. The Erichsen cupping tests showed similar Erichsen values (5.60 mm and 5.67 mm) for de-coated and coated welded joints. An opposite effect of ferrite on Erichsen cupping tests was obtained. The peak force required for deformation dropped by 35% with Al-10wt.%Si coating.
关键词： Microstructure,Al-Si coating,Mechanical properties,Fiber laser welding,22MnB5 steel
更新于2025-11-28 14:24:20
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Tailoring the collagen film structural properties via direct laser crosslinking of star-shaped polylactide for robust scaffold formation
摘要： Application of restructured collagen-based biomaterials is generally restricted by their poor mechanical properties, which ideally must be close to those of a tissue being repaired. Here, we present an approach to the formation of a robust biomaterial using laser-induced curing of a photosensitive star-shaped polylactide. The created collagen-based structures demonstrated an increase in the Young’s modulus by more than an order of magnitude with introduction of reinforcing patterns (from 0.15±0.02 MPa for the untreated collagen to 51.2±5.6 MPa for the reinforced collagen). It was shown that the geometrical configuration of the created reinforcing pattern affected the scaffold’s mechanical properties only in the case of a relatively high laser radiation power density, when the effect of accumulated thermomechanical stresses in the photocured regions was significant. Photo-crosslinking of polylactide did not compromise the scaffold’s cytotoxicity and provided fluorescent regions in the collagen matrix, that create a potential for noninvasive monitoring of such materials’ biodegradation kinetics in vivo.
关键词： mechanical properties,collagen,reinforcements,photopolymerization,biocompatible polymers,riboflavin
更新于2025-11-21 11:24:58
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Structural and optical studies on PVA capped SnS films grown by chemical bath deposition for solar cell application
摘要： Tin monosulphide (SnS) thin films capped by PVA have been successfully deposited on glass substrates for cost effective photovoltaic device applications by a simple and low-cost wet chemical process, chemical bath deposition (CBD) at different bath temperatures varying in the range, 50–80 °C. X–ray diffraction analysis showed that the deposited films were polycrystalline in nature, showing orthorhombic structure with an intense peak corresponding to (040) plane of SnS. These observations were further confirmed by Raman analysis. FTIR spectra showed the absorption bands which corresponds to PVA in addition to SnS. The scanning electron microscopy and atomic force microscopy studies revealed that the deposited SnS films were uniform and nanostructured with an average particle size of 4.9 to 7.6 nm. The optical investigations showed that the layers were highly absorbing with the optical absorption coefficient ~105 cm–1. A decrease in optical band gap from 1.92 to 1.55 eV with an increase of bath temperature was observed. The observed band gap values were higher than the bulk value of 1.3 eV, which might be due to quantum confinement effect. The optical band gap values were also used to calculate particle size and the results are discussed.
关键词： structural properties,optical properties,SnS thin films,polyvinyl alcohol,capping agent,chemical bath deposition
更新于2025-11-21 11:18:25