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Effects of laser surface melting on crystallographic texture, microstructure, elastic modulus and hardness of Tia??30Nba??4Sn alloy
摘要： The biocompatibility of orthopedic implants is closely related to their elastic modulus and surface properties. The objective of this study was to determine the effects of cold rolling, recrystallization and laser surface melting (LSM) on the microstructure and mechanical properties of a biphase (α″+β) Ti?30Nb?4Sn alloy. X-ray diffraction (XRD) texture analysis of the cold-rolled substrate revealed the [302]α″//ND texture component, while analysis of the recrystallized substrate showed the [302]α″//ND and [110]α″//ND components. The β-phase texture could not be directly measured by XRD, but the presence of the [111]β//ND texture component was successfully predicted by considering the orientation relationship between the α″ and β phases. Nanoindentation measurements showed that the elastic modulus of the cold-rolled substrate (63 GPa) was lower than that of the recrystallized substrate (74 GPa). Based on the available literature and the results presented here, it is suggested that this difference is caused by the introduction of crystal defects during cold deformation. The combined nanoindentation/EBSD analysis showed that the nanoindentation results are not affected by crystal orientation. LSM of the deformed alloy produced changes in hardness, elastic modulus and crystallographic texture similar to those produced by recrystallization heat treatment, creating a stiffness gradient between surface and substrate.
关键词： laser surface melting,stiffness-graded material,crystallographic texture,cold rolling,titanium alloy,recrystallization
更新于2025-09-23 15:21:01
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Fatigue behaviors of foreign object damaged Ti-6Al-4V alloys under laser shock peening
摘要： Two-sided and simultaneous laser shock peening (TSLSP) was used to strengthen the Ti-6Al-4V titanium alloy. The fatigue crack growth rate of the specimens was investigated by fatigue test. The results show that both direct TSLSP (TSLSP-D) and indirect TSLSP (TSLSP-I) can reduce the fatigue crack growth rate by producing high magnitude compressive residual stress. The maximum fatigue life increases by 94% (TSLSP-D) and 169% (TSLSP-I) compared with the original specimens. Moreover, the TSLSP-D results show decreased resistance to foreign object damage because of decreased plasticity while the TSLSP-I simultaneously achieves superior foreign object damage resistance and fatigue performance.
关键词： Fatigue performance,Foreign object damage,Two-sided and simultaneous laser shock peening,Titanium alloy
更新于2025-09-23 15:21:01
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Laser printing of micro-electronic communication systems for smart implants applications
摘要： Endow the implant with intrinsic communication system between sensors and actuators or between implant and patient is a key factor for its long-term success. The capacity of early diagnosis of failures and the ability to remedy them are necessary to minimize expensive complications and reducing revision procedures. Ti6Al4V is the most used titanium alloy for implant’s fabrication. In this sense, this work presents a promising approach to print communication systems by using laser technology, aiming integrate the smart components on titanium implants. Laser has been employed as a versatile tool to modify the surface in different ways, such as texturing, oxidizing and sintering. Silver wires have been printed on Ti6Al4V surface in order to conduct electrical current. To minimize current loss for the substrate, titanium oxide layer has been produced by different methods (laser and anodization). Laser sintering (LS) has been also compared to a conventional method (Hot-pressing- HP) to consolidate the silver powder into the cavities. In comparison to the conventional techniques, laser demonstrated to be a competitive approach to oxidizing the surface and also for consolidating the micro-wires on Ti6Al4V surface. Consequently, the micro-wires printed by laser approach presented satisfactory results in terms of electrical resistance, actuating as the conductor path for electrical current, with values of 0.0131 Ω, which is similar to the resistance of the wire printed in an insulator substrate.
关键词： Ti6Al4V titanium alloy,Laser oxidation,Implants,Laser surface modification,Nd:YAG laser,Laser sintering
更新于2025-09-23 15:21:01
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Microstructure and properties of Tia??Zr congruent alloy fabricated by laser additive manufacturing
摘要： In the present work, Ti40Zr (atomic percent) congruent alloy, as well as four other Ti-Zr alloys near the congruent point, was fabricated using laser additive manufacturing (LAM) on pure titanium substrate. Comparative analyses of these alloys were performed based on microstructure, mechanical properties, tribological properties, corrosion resistance, and formability. The results show that the microstructure of the alloys develops sequentially from the Widmanst?tten structure to nearly full b -(TiZr) columnar crystals for 40 at.% Zr, to b -(TiZr) columnar crystals plus granular a -(TiZr) with the increase of Zr addition. The Ti60Zr40 congruent alloy with nearly full b -(TiZr) structure presents a novel combination of ductility, corrosion resistance, and formability, but it has a slightly lower hardness, less strength and poor tribological properties, compared with the other Ti-Zr alloys near the congruent point. Therefore, to develop the congruent alloy as a high strength LAM material through alloying is very significant.
关键词： Congruent Alloy,Laser additive manufacturing,Titanium alloy,Properties,Microstructure
更新于2025-09-23 15:19:57
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Effects of laser shock peening on microstructure and fatigue behavior of Tia??6Ala??4V alloy fabricated via electron beam melting
摘要： Laser shock peening (LSP) is a post-treatment process that is widely used to modify the surface microstructure and mechanical properties of parts constructed by additive manufacturing (AM). In this study, the influence of LSP on the microstructure and fatigue behavior of Ti–6Al–4V alloy manufactured via electron beam melting (EBM), a popular method of AM, was investigated. The microstructure of the EBM sample consisted of the β phase (~6 vol%) and α lamellar phase. Grain refinement of the α phase occurred via both dislocation evolution and deformation twinning during LSP. A theoretical description of the microstructural evolution, particularly the distribution of deformation twins, was developed. The fatigue strength and micro-hardness of the EBM samples increased by approximately 17% and 11% after LSP treatment, respectively. The fatigue fracture morphologies at three defined damage stages (crack initiation, crack propagation, and instantaneous rupture) were examined for EBM samples before and after LSP. The dominant mechanism of fatigue strength enhancement by LSP was discussed. The effects of residual compressive stress assistant with adiabatic temperature increase and grain refinement of the α phase produced by LSP reduced the pre-existing crack size, suppressed crack initiation, and increased the required work for fatigue fracture.
关键词： Laser shock peening,Electron beam melting,Ti–6Al–4V titanium alloy,Fatigue behavior,Microstructural characterization
更新于2025-09-23 15:19:57
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Study of the effect of surface laser texture on tribological properties of cemented carbide materials
摘要： Surface texturing has become a potential method to obtain a low friction coefficient under dry/lubricated conditions for different mechanical product surfaces. The mechanism of friction and wear reduction from a micro-texture on the surface of cemented carbide cutting tools was investigated by dry cutting a titanium alloy. Three kinds of micro-textures, namely, line, sinusoidal and rhombic grooves, with different area occupancy rates were produced by a laser on the cemented carbide surface. Experiments and finite element simulation of ABAQUS were used to investigate the tribological characteristics of micro-textured cemented carbide. The results indicated that the line-textured cemented carbide with an area occupancy rate of 10% showed a low friction coefficient of 0.076, which is approximately 34% of the non-textured sample. Few adhesives appeared on the textured surface, while a large number of adhesives were attached to the smooth surface after 30 min of dry friction between the cemented carbide and the titanium alloy balls. Moreover, among the three textures, the line-groove texture has the smallest friction coefficient and a good anti-wear effect. The results show that the existence of a groove texture can effectively reserve the wear debris, reduce the bond wear and weaken the furrow effect.
关键词： titanium alloy,friction and wear,Cemented carbide,machine tool and chip contact zone,surface texture
更新于2025-09-23 15:19:57
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Enhancing Hardness and Wear Performance of Laser Additive Manufactured Ti6Al4V Alloy Through Achieving Ultrafine Microstructure
摘要： Refining microstructure is an important issue for laser additive manufacturing (LAM) of titanium alloy. In the present work, the microstructures of LAM-fabricated Ti6Al4V alloy were refined using a low energy density with the combination of a small spot diameter, a low laser power, and a high scanning speed. The microstructure, hardness, wear performance, and molten pool thermal behavior of LAM-fabricated Ti6Al4V coatings were studied. The results show that the grain sizes of both prior β and α phases are strongly dependent on the cooling rate of the molten pool. The fine prior β grains and submicron-scale acicular α phases were obtained under a low energy density of 75 J mm?2 due to the high cooling rate of the molten pool. In addition, the as-fabricated Ti6Al4V sample with submicron-scale acicular α phase showed a very high hardness of 7.43 GPa, a high elastic modulus of 133.6 GPa, and a low coefficient of friction of 0.48. This work provides a good method for improving the microstructure and mechanical performance of LAM-fabricated Ti6Al4V alloy.
关键词： wear properties,hardness,laser additive manufacturing,titanium alloy,microstructure
更新于2025-09-23 15:19:57
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Surface and subsurface characteristics of laser polished Ti6Al4V titanium alloy
摘要： This paper aims at investigating the effects of laser power, laser pulse repetition rate and scan speed on the polished metal surface and subsurface characteristics. The influence of initial surface roughness of workpiece on the polishing performance was also taken into account. In this study, Ti6Al4V titanium alloy was selected as a specimen to be polished by a nanosecond pulse laser. The results revealed that the surface roughness was able to be improved by about 43% when the laser fluence of 1–3 J/cm2 was applied. In addition, the proper polishing condition was dependent on the initial surface roughness of workpiece, and a better surface improvement was subjected to a lower initial surface roughness. A thick recast layer, high degree of oxidation and large heat-affected zone with lots of micro-cracks were obtained when too high laser power and slow scan speed were used in the polishing of titanium alloy. With regard to the findings of this study, the suggested polishing conditions could be applied for smoothing the different levels of initial surface roughness of titanium alloy and possibly other similar metals with less subsurface damage.
关键词： Surface roughness,Polishing,Titanium alloy,Laser
更新于2025-09-23 15:19:57
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Effects of groove constraint space on plasma characteristics during Laser-MIG hybrid welding of Titanium alloy
摘要： Laser-MIG hybrid welding with groove shows great potential in thick plate joining. However, the plasma behaviors in?uenced by the groove space are not well understood. In this paper, special stair-stepping plates with groove were designed to form di?erent groove con?gurations, and the e?ects of groove depth on the plasma characteristics were investigated systematically. The results showed that the plasma temperature decreased from 10,589 K to 8,527 K and the electron density increased from 1.30 × 1016 cm?3 to 1.44 × 1016 cm?3 when the groove depth increased from 0 to 20 mm. The reason may be that more laser-induced metal vapor, cooler than arc plasma, cannot leave the deeper groove space in time. The heat convection and radiation between the vapor and plasma resulted in the temperature decrease. Besides, as the groove constraint space increased, the plasma pro?le, frequency of droplet-transfer and weld width decreased, while the penetration depth increased to some extent. This research results would be inspirational and meaningful to the laser-arc hybrid welding of medium and thick plate.
关键词： Plasma,Titanium alloy thick plate,Laser-MIG hybrid welding,Groove constraint space
更新于2025-09-16 10:30:52
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Obtaining Spherical Powders of Grade 5 Alloy for Application in Selective Laser Melting Technology
摘要： In this paper, the process of obtaining a spherical powder of titanium alloy of the grade 5 brand using inductively coupled argon-helium plasma has been studied. The structure of titanium alloy was studied before and after the spheroidization process. The results of particle size and X-ray fluorescent analysis were also obtained. As a result of the analysis of the structure, it was concluded that the crystallite sizes and microstress values change.
关键词： plasmachemical synthesis,additive technology,titanium alloy,spheroidization,grade 5
更新于2025-09-16 10:30:52