Structure of 3D Printed Ti-6Al-4V Alloy after Low-frequency Processing

The structure and residual elastic stresses in 3D printed (Selective laser melting) Ti-6A1-4V samples after the low-frequency vibration processing were investigated. The studied samples were manufactured horizontally in respect to the building platform. Different vibration oscillations modes (vertical, horizontal, and elliptical) were chosen for study. The oscillations were done with frequency of 16 Hz, and a processing time was 20 minutes. Studies shown that 3D printed samples had a high level of residual elastic stresses, which were changed after vibration treatment. The influence of the low-frequency processing on the phase composition of the alloy was found. © Published under licence by IOP Publishing Ltd

Comparative analysis of the structure and internal stress in Ti-6Al-4V alloys manufactured by 3D printing and processing with screw extrusion

Study is based on the compare characterization of the structure and evaluation of the residual internal stresses in Ti-6Al-4V samples manufactured by the 3D printing (selective laser melting) and in the Ti-6Al-4V samples obtained with using of the severe plastic deformation by screw extrusion. The microstructure and residual stresses were examined by transmission electron microscope and X-ray diffractometer. High tensile internal residual stresses in the 3D printed sample were found. The high compressive residual internal stresses were found in the hot pressed and in the twisted samples. It was shown that arising of the high residual stresses in the studied samples under various technological processes occurred in various ways. The residual stresses in the severe plastic deformed samples arose due to non-uniform volumetric plastic deformation. In 3D printed sample, the residual tensile stresses arose from both phase (martensitic) transformation and thermal deformation. © Published under licence by IOP Publishing Ltd

Microstructure and mechanical properties of Al-12Si produced by selective laser melting

Al-12Si specimens are produced by selective laser melting (SLM) from gas atomized powders. Installation for the production of powder is original. All specimens were prepared using the EOSINT M 280 device. A fine cellular structure is observed with residual free Si along the cellular boundaries. Room temperature tensile tests reveal remarkable mechanical behavior: the samples show yield and tensile strengths of about 102 MPa and 425 MPa, respectively, along with fracture strain of 12%. The study of crack surface morphology was shown by the example of a sample. Except the spherical pores, the interface of the molten pool also appears on the fracture surface, which indicates a mixture of fragile and ductile fracture. Additionally, the agglomerated silicon group appears also on the fracture surface. © Published under licence by IOP Publishing Ltd

Microstructure and mechanical properties of Al-12Si produced by selective laser melting

Al-12Si specimens are produced by selective laser melting (SLM) from gas atomized powders. Installation for the production of powder is original. All specimens were prepared using the EOSINT M 280 device. A fine cellular structure is observed with residual free Si along the cellular boundaries. Room temperature tensile tests reveal remarkable mechanical behavior: the samples show yield and tensile strengths of about 102 MPa and 425 MPa, respectively, along with fracture strain of 12%. The study of crack surface morphology was shown by the example of a sample. Except the spherical pores, the interface of the molten pool also appears on the fracture surface, which indicates a mixture of fragile and ductile fracture. Additionally, the agglomerated silicon group appears also on the fracture surface. © Published under licence by IOP Publishing Ltd

Oxygen and nitrogen concentrations in the Ti-6Al-4V alloy manufactured by direct metal laser sintering (DMLS) process

Published ArticleTwo machines from two scientific centers (Russia and South Africa) were used for the manufacturing of the Ti6Al4V alloys by the direct metal laser sintering. The chemical composition of powders complies with the ASTM F-136 (grade 5), ASTM B348 (grade 23) standard for medical applications. Analysis of the oxygen and nitrogen contamination in DMLS alloys was done with Van de Graaff accelerator with two Mega Volts. It is found that structures of the samples manufactured with two different machines used the same regimes are close to each other. TEM studies found the metastable martensitic structure and silicon nitride Si3N4. It was found that the oxygen and nitrogen contents in both samples are within the normal range for medical grade titanium alloys

Structural and micromechanical properties of 316L stainless steel produced by selective laser melting

The structure and micromechanical properties of a 316L stainless steel produced by the selective laser melting (SLM) technique have been studied in its initial state and the following heat treatment: quenching from 1050 ºС and 4-hour annealing at 480 ºС. The heat treatment does not result in changing the steel phase composition, however, it reduces the microhardness by 5%, HM hardness (Martens hardness) by 12% and indentation hardness by 16% at HIT maximum load. The heat treatment also increases the Е* contact elasticity modulus by 14% due to the lower porosity of the material. As soon as heat treatment provides no strengthening of the steel synthesized by SLM, deformation processing, chemicothermal treatment and application of thin coatings may become quite promising strengthening methods. © 2020 Institute of Physics Publishing. All rights reserved.The main results were funded by the RFBR and Sverdlovsk Oblast, project number 20-48-660065. The results of the electron diffraction phase analysis were obtained by the M.N. Mikheev Institute of Metal Physics of the Ural Branch of the Russian Academy of Sciences (IMP UB RAS) within the state assignment of Ministry of Science and Higher Education of the Russian Federation (theme “Structure” No. № АААА-А18-118020190116-6). The studies were performed at the collaborative access center “Testing center of nanotechnology and advanced materials” of IMP UB RAS

ФОРМИРОВАНИЕ СКВОЗНЫХ СТРУКТУР С РАЗЛИЧНОЙ ПОРИСТОСТЬЮ НА ТОЛСТЫХ ПЛАСТИНАХ МОНОКРИСТАЛЛИЧЕСКОГО КРЕМНИЯ

Through three−layered structure has been formed on silicon wafers 500 microns thick by electrochemical etching in a solution of hydrofluoric acid without using additional deletions monocrystalline layers. The resulting structures are divided into two types. The first type pass−through structure comprises two outermost macroporous silicon layers 220—247,5 microns thick with a pore diameter 7—10 microns and an average mesoporous silica layer 5—60 microns thick with a pore diameter of 100—150 nm. The second type pass−through structure includes macroporous silicon layer 250 microns in thickness, interlocking in the depth of the silicon wafer to form a cavity the size of 4—8 microns. The developed technology will allow forming monolithic structures of membrane−electrode assembly microfuel elements in an easier and more reliable manner.Электрохимическим травлением в растворах концентрированной плавиковой кислоты получены сквозные трехслойные структуры двух типов на пластинах монокристаллического кремния толщиной 500 мкм без применения дополнительных операций удаления монокристаллических слоев. Сквозная структура первого типа содержит крайние два слоя макропористого кремния толщиной 220—247,5 мкм с диаметром пор 7—10 мкм и средний слой мезопористого кремния толщиной 5—60 мкм с диаметром пор от 100 до 150 нм. Сквозная структура второго типа состоит из слоев макропористого кремния толщиной 250 мкм, смыкающихся в глубине пластины кремния посередине с образованием полостей размером 4—8 мкм. Разработана технология, которая позволяет более просто и надежно формировать монолитный каркас мембранно-электродного блока микротопливного элемента

Phase Precipitations in Dental Co–Cr–Mo Alloy Samples Manufactured by 3D Laser Printing

Проведен сравнительный анализ химического состава и кристаллической решетки выделений в образцах Co–Cr–Mo, изготовленных на 3 Д-принтере EOSINT M280. Установлено, что выделения принадлежат интерметаллидной сигма-фазе Co2 (Mo, Cr)3 и метастабильным фазам внедрения, которые представляют собой полиморфные модификации монооксида кобальта (h-CoO) и силиката SiO2 (crystobalite high).Comparative analysis of the chemical composition and crystal lattice of the precipitations in the Co–Cr–Mo samples manufactured with EOSINT M280 3D printer was done. The intermetallic sigma phase Co2 (Mo, Cr)3 and metastable interstitial phases which are polymorph modifications of cobalt monoxide (h-CoO) and silicate SiO2 (Crystobalite high) were observed by TEM.Работа выполнена в рамках государственного задания Минобрнауки России (тема «Аддитивность», № 121102900049-1).The work was carried out within the framework of the state task of the Ministry of Education and Science of Russia (topic “Additivity”, No. 121102900049-1)