EFFECT OF TEMPERATURE OF SOLID SOLUTION TREATMENT ON MECHANICAL PROPERTIES OF AN Al-Cu-Mg ALUMINUM ALLOY

Исследовано влияние температуры обработки на получение пересыщенного твердого раствора на условный предел текучести, предел прочности, относительное удлинение до разрушения и равномерное удлинение авиационного термоупрочняемого алюминиевого сплава Al-Cu-Mg. Установлено, что с ростом температуры обработки увеличиваются как прочностные, так и пластические характеристики материала. Наилучшие механические свойства наблюдаются после обработки на получения пересыщенного твердого раствора при температуре 510 °С и составляют: условный предел текучести – 180 МПа, предел прочности – 395 МПа, относительное удлинение – 25%.The effect of the temperature of the solid solution treatment on the yield stress, ultimate tensile stress, elongation to failure, and uniform elongation of a heatresistance Al-Cu-Mg alloy for aircraft was studied. The strength and plasticity increased with processing temperature. The best combination of mechanical properties was observed after solution treatment at a temperature of 510 °C. The yield stress, ultimate tensile stress, and elongation were achieved at 180 MPa, 395 MPa, and 25%, respectively.Работа выполнена при финансовой поддержке Министерства науки и высшего образования Российской Федерации, код научной темы FZWG-2023-0005 «Природа влияния холодной пластической деформации на фазовые превращения и свойства алюминиевых сплавов». Исследование выполнено с использованием оборудования Центра коллективного пользования "Технологии и Материалы НИУ "БелГУ"

EFFECT OF PRE-STRETCHING AND NATURAL AGEING ON THE MECHANICAL BEHAVIOUR OF HIGH STRENGTH Al–Cu-Mg ALLOY

В работе было исследовано влияние предварительной деформации и естественного старения на микроструктуру и механические свойства высокопрочного сплава AA2519 (по классификации Aluminum Association). Дефекты кристаллической решетки, привнесенные деформацией, оказывают значительное влияние на характер упрочняющих выделений после естественного старения. Продемонстрировано что небольшая деформация растяжением после естественного старение приводит к дополнительному значительному увеличению прочностных характеристик, при сохранении пластичности.The work investigated the effect of pre-deformation and natural ageing on the microstructure and mechanical properties of the high-strength alloy AA2519 (on the Aluminum Association classification). Introduced crystalline defects have a significant impact on the nature of the strengthening precipitates after natural ageing. It has been demonstrated that a small percent of pre-stretching after natural ageing leads to a significant increase in strength, while elongation to failure exceeds 20%.Работа выполнена при финансовой поддержке Министерства науки и высшего образования Российской Федерации, код научной темы FZWG-2023-0005 «Природа влияния холодной пластической деформации на фазовые превращения и свойства алюминиевых сплавов», с использованием оборудования Центра коллективного пользования "Технологии и Материалы НИУ "БелГУ"

MICROSTRUCTURE AND PHASE COMPOSITION OF Zr-MODIFIED ALUMINUM ALLOY AA2624 AFTER SEMI-CONTINUOUS CASTING AND HOMOGENISATION

Алюминиевый сплав АА2624 (Al-Cu-Mg) с добавками циркония был получен методом полунепрерывного литья с высокой скоростью кристаллизации. В литом состоянии сплав имеет дендритную структуру с избыточными фазами, расположенными по границам ячеек. Энергодисперсионный анализ выявил наличие -фазы (Al) и эвтектической S-фазы (Al2CuMg), выделяющейся по границам ячеек. Доля S-фазы составила 24,8±12,1%. Гомогенизационный отжиг приводит к растворению избыточной S-фазы с уменьшением доли до 6,8±1,8%. Медленное охлаждение с печью приводит к распаду твердого раствора меди и магния в алюминии с выделением мелких частиц в форме реек в теле дендритной ячейки.Aluminum alloy AA2624 with Zr additives was produced by semi-continuous casting. The alloy in the cast condition has a dendritic structure with excess phases located along the boundaries of dendritic cells. Al and a eutectic S-phase (Al2CuMg), produced along the cell boundaries, were detected by energy-dispersive X-ray spectroscopy. The volume fraction of the S-phase is 24,8±12,1%. Homogenization annealing leads to the dissolution of excess S-phase with a decrease in volume fraction to 6,8±1,8%. Slow cooling with a furnace leads to the decomposition of the solid solution of magnesium copper in aluminum with the release of small particles in the form of laths in the dendritic cell.Работа выполнена при финансовой поддержке Министерства науки и высшего образования Российской Федерации, код научной темы FZWG-2023-0005 «Природа влияния холодной пластической деформации на фазовые превращения и свойства алюминиевых сплавов», с использованием оборудования Центра коллективного пользования "Технологии и Материалы НИУ "БелГУ"

Regularities of Microstructure Evolution in a Cu-Cr-Zr Alloy during Severe Plastic Deformation

The effect of severe plastic deformation by the conforming process of equal channel angular extrusion (ECAE-Conform) followed by cold rolling on the microstructures developed in a Cu-0.1Cr-0.1Zr alloy was investigated. Following the ECAE-Conform of 1 to 8 passes (corresponding strains were 0.8 to 6.4) cold rolling to a total strain of 4 was accompanied by substantial grain refinement and strengthening. An average grain size tended to approach 160 nm with an increase in the rolling reduction. An increase in the ECAE-Conform strain promoted the grain refinement during subsequent cold rolling. The fraction of the ultrafine grains with a size of 160 nm after cold rolling to a strain of 4 increased from 0.12 to 0.52 as the number of ECAE-Conform passes increased from 1 to 8. Correspondingly, the yield strength increased above 550 MPa. The strengthening could be expressed by a Hall–Petch type relationship with a grain size strengthening factor of 0.11 MPa m0.5

AlSi10Mg/AlN Interface Grain Structure after Laser Powder Bed Fusion

Details and features of the grain structure near the interface region between the AlN ceramic phase and AlSi10Mg matrix after the laser powder bed fusion (LPBF) were investigated. Aluminum nitride particles were obtained through self-propagating high-temperature synthesis and mechanically mixed with aluminum matrix powder. Optimization of the LPBF process parameters resulted in synthesized material free of pores and other defects. Optical microscopy analysis of etched cross-section and more detailed EBSD analysis revealed regions with relatively coarse grains at melting pool boundaries and fine grains in the melt pool core and near the AlN particles. Moreover, a pronounced orientation of fine elongated matrix grains towards the center of the ceramic particle was obtained. The such formed microstructure is attributed to directional heat sink during crystallization due to the higher thermal conductivity of aluminum nitride compared to the AlSi10Mg matrix. On the contrary, poor wettability of AlN by melt partly prevented the formation of such features, thus a combination of these factors determines the final microstructure of the interface in the resulting material

AlSi10Mg/AlN Interface Grain Structure after Laser Powder Bed Fusion

Details and features of the grain structure near the interface region between the AlN ceramic phase and AlSi10Mg matrix after the laser powder bed fusion (LPBF) were investigated. Aluminum nitride particles were obtained through self-propagating high-temperature synthesis and mechanically mixed with aluminum matrix powder. Optimization of the LPBF process parameters resulted in synthesized material free of pores and other defects. Optical microscopy analysis of etched cross-section and more detailed EBSD analysis revealed regions with relatively coarse grains at melting pool boundaries and fine grains in the melt pool core and near the AlN particles. Moreover, a pronounced orientation of fine elongated matrix grains towards the center of the ceramic particle was obtained. The such formed microstructure is attributed to directional heat sink during crystallization due to the higher thermal conductivity of aluminum nitride compared to the AlSi10Mg matrix. On the contrary, poor wettability of AlN by melt partly prevented the formation of such features, thus a combination of these factors determines the final microstructure of the interface in the resulting material