Ultrafine grain evolution in a Cu-Cr-Zr alloy during warm multidirectional forging

The microstructure evolution and the deformation behavior of a Cu-0.3%Cr-0.5%Zr alloy subjected to multidirectional forging at a temperature of 673 K under a strain rate of about 10-³ s-¹ were studied. Following a rapid increase in the flow stress during straining to about 1, the strain hardening gradually decreases, leading to a steady-state flow behavior at total strain above 2. The multidirectional forging led to the development of ultrafine grained microstructures with mean grain sizes of 0.9 μm and 0.64 μm in the solution treated and aged samples, respectively. The presence of second phase precipitates promoted the grain refinement. After processing to a total strain of 4, the fractions of ultrafine grains (D < 2 μm) comprised 0.36 and 0.59 in the solution treated and aged samples, respectivel

Método de obtención de la fase beta estable de un metal puro de transición del grupo IV del sistema periódico y producto obtenible por dicho método

Método de obtención de la fase beta estable de un metal puro de transición del grupo IV del sistema periódico y producto obtenible por dicho método. Se describe un nuevo método para la fabricación controlada de la fase beta de los metales de transición del grupo IV del sistema periódico que es estable en condiciones ambiente (1 atmósfera y 22ºC). El procedimiento comprende una primera etapa de aplicación, sobre una muestra (2) elaborada de la fase alfa del metal de transición considerado, de una presión de compresión de un valor mínimo de entre 1 y 3 GPa, seguida de una segunda etapa de aplicación, manteniendo dicha presión, de una deformación de cizalladura, de valor mínimo no superior a 39.2. El procedimiento descrito permite obtener fase beta estable de metales de transición del grupo IV empleando presiones y cizalladuras de valores sensiblemente inferiores que en el caso de obtención de dicha fase beta estable por medios que no implican aplicación simultánea de presión y cizalladura.Peer reviewedConsejo Superior de Investigaciones Científicas (España), Instituto Madrileño de Estudios AvanzadosA1 Solicitud de patente con informe sobre el estado de la técnic

In-situ nanocomposite in friction stir welding of 6061-T6 aluminum alloy to AZ31 magnesium alloy

Prior to friction stir welding (FSW), silicon carbide (SiC) nanopowders were placed inside the groove on the adjacent side of magnesium sheet. In order to make a good distribution of these nanoparticles, first, friction stir processing (FSP) with a pinless tool was conducted on this side. Second, using a frustum pin tool, a combination of two travel speeds (25 and 35¿mm/min) and three rotation speeds (550, 600 and 650¿rpm) were employed to obtain the optimal conditions for FSW of AZ31 magnesium alloy to 6061 aluminum alloy. The joint fabricated at 35¿mm/min and 650¿rpm, exhibited improvement of 28% in tensile strength and enhancement about three times in elongation, compared with the joint without nanoparticles. SiC nanoparticles had an effective role on the grain refining of the stirred zone and improving the microstructural characteristics of the banded structure zone. Due to the decreased grain size and the presence of ceramic nanoparticles (SiC) with high value of hardness, the hardness level of the reinforced samples was greater than that of the non-reinforced samples. Fracture of the non-reinforced sample was completely brittle, while in the reinforced samples, fracture features changed to the ductile mode.Peer ReviewedPostprint (author's final draft

Fundamentals of interface phenomena in advanced bulk nanoscale materials

The review is devoted to a study of interface phenomena influencing advanced properties of nanoscale materials processed by means of severe plastic deformation, high-energy ball milling and their combinations. Interface phenomena include processes of interface defect structure relaxation from a highly nonequilibrium state to an equilibrium condition, grain boundary phase transformations and enhanced grain boundary and triple junction diffusivity. On the basis of an experimental investigation, a theoretical description of the key interfacial phenomena controlling the functional properties of advanced bulk nanoscale materials has been conducted. An interface defect structure investigation has been performed by TEM, high-resolution x-ray diffraction, atomic simulation and modeling. The problem of a transition from highly non-equilibrium state to an equilibrium one, which seems to be responsible for low thermostability of nanoscale materials, was studied. Also enhanced grain boundary diffusivity is addressed. Structure recovery and dislocation emission from grain boundaries in nanocrystalline materials have been investigated by analytical methods and modeling

Особенности течения инфекционного артрита у пациента с гипогаммаглобулинемией

Hypogammaglobulinemia is a condition caused by low levels of immunoglobulins in the blood serum. It can be a manifestation of primary immunodeficiency, characterized by a violation of the production of immunoglobulins, in particular common variable immunodeficiency (CVID). A typical clinical sign of CVID is various severe infections, among which infectious arthritis is not uncommon. At the same time, the clinical picture of infections can differ significantly from that in individuals with a normal immune response, including the spectrum of infectious arthritis pathogens.The article describes a clinical case of an unusual course of infectious arthritis in a patient with newly diagnosed hypogammaglobulinemia. The peculiar features of the case were a long (more than 1.5 years) course of the disease, without the development of septic complications, no increase in ESR and CRP, recurrence of arthritis after a 2-month course of antibiotic therapy, and the presence of generalized edema. The causes and diagnosis, features of infectious complications, including infectious arthritis, and probable causes of edematous syndrome in CVID are discussed.Гипогаммаглобулинемия – состояние, обусловленное низким уровнем иммуноглобулинов в сыворотке крови. Она может быть проявлением первичного иммунодефицита, характеризующегося нарушением продукции иммуноглобулинов, в частности общей вариабельной иммунной недостаточностью (ОВИН). Типичным клиническим признаком ОВИН являются различные инфекции тяжелого течения, среди которых нередки и инфекционные артриты. При этом клиническая картина инфекций может значительно отличаться от таковой у лиц с нормальным иммунным ответом, в том числе спектром возбудителей инфекционного артрита. В статье описано клиническое наблюдение необычного течения инфекционного артрита у пациента с впервые выявленной гипогаммаглобулинемией. Особенностями случая были длительное (более 1,5 лет) течение заболевания без развития септических осложнений, отсутствие повышения СОЭ и СРБ, рецидив артрита после 2-месячного курса антибактериальной терапии, а также наличие генерализованных отеков. Обсуждаются причины и диагностика, особенности инфекционных осложнений, в том числе инфекционных артритов, и вероятные причины отечного синдрома при ОВИН

Peak Stir Zone Temperatures during Friction Stir Processing

The stir zone (SZ) temperature cycle was measured during the friction stir processing (FSP) of NiAl bronze plates. The FSP was conducted using a tool design with a smooth concave shoulder and a 12.7-mm step-spiral pin. Temperature sensing was accomplished using sheathed thermocouples embedded in the tool path within the plates, while simultaneous optical pyrometry measurements of surface temperatures were also obtained. Peak SZ temperatures were 990 ⁰Cto 1015 ⁰C (0.90 to 0.97 TMelt) and were not affected by preheating to 400⁰C, although the dwell time above 900 ⁰C was increased by the preheating. Thermocouple data suggested little variation in peak temperature across the SZ, although thermocouples initially located on the advancing sides and at the centerlines of the tool traverses were displaced to the retreating sides, precluding direct assessment of the temperature variation across the SZ. Microstructure-based estimates of local peak SZ temperatures have been made on these and on other similarly processed materials. Altogether, the peak-temperature determinations from these different measurement techniques are in close agreement

New forming method of manufacturing cylindrical parts with nano/ultrafine grained structures by power spinning based on small plastic strains

A new spinning method to manufacture the cylindrical parts with nano/ultrafine grained structures is proposed, which consists of quenching, power spinning and recrystallization annealing. The microstructural evolution during the different process stages and macroforming quality of the spun parts made of ASTM 1020 steel are investigated. The results show that the microstructures of the ferrites and pearlites in the ASTM 1020 steel are transformed to the lath martensites after quenching. The martensite laths obtained by quenching are refined to 87 nm and a small amount of nanoscale deformation twins with an average thickness of 20 nm is generated after performing a 3-pass stagger spinning with 55% thinning ratio of wall thickness, where the equivalent strain required is only 0.92. The equiaxial ferritic grains with an average size of 160 nm and nano-carbides are generated by subsequent recrystallization annealing at 480°C for 30 min. The spun parts with high dimensional precision and low surface roughness are obtained by the forming method developed in this work, combining quenching with 3-pass stagger spinning and recrystallization annealing

Возможности прогнозирования интерстициального заболевания легких у больных системной склеродермией: результаты наблюдательного исследования

In patients with systemic sclerosis (SSc), interstitial lung disease (ILD) is a factor in the decline of functional capacity up to disability and is also the leading cause of death. Therefore, one of the most important tasks in the treatment of this group of patients is not only to detect involvement of respiratory system, but also to predict the likelihood of its development.Objective: to study the possibility of predicting the development of ILD and advanced ILD in patients with SSc.Material and methods. The study included 79 patients with SSc (mean age 64.4±11.5 years; 94.9% women) from the Registry of myositis, SSc and Mixed Connective Tissue Diseases (РЕМИССиС) who underwent high-resolution computed tomography (HRCT) of the lungs. Classification trees (CTr) were constructed to predict the development of widespread ILD using the CHAID algorithm (exhaustive). All patients were tested for antibodies against Scl-70 (anti-Scl-70), CENP-B (anti-CENP-B), and PmScl (anti-PmScl).Results and discussion. ILD signs according to HRCT were detected in 53 patients. Fibrotic (34.2%) and cellular (15.2%) types of nonspecific interstitial pneumonia were the most common, and common interstitial pneumonia was less frequent (11.4%).The presence of ILD and advanced ILD (involvement of more than 20% of the lung parenchyma) were significantly associated with the detection of any autoantibodies, except anti-centromere antibodies, an increase in pulmonary artery systolic pressure, a decrease in forced vital capacity, diffusing capacity of the lungs, blood oxygen saturation at rest, and all parameters of six-minute walk test (6MWT), and complaints of shortness of breath. In addition, the presence of extensive ILD was also significantly associated with diffuse SSc and with SSc without skin manifestations.In establishing the CTr, it was found that the development of widespread ILD was unlikely in individuals who were able to walk more than 440 m in 6MWT and had neither anti-Scl-70 nor anti-PmScl.Significant associations were also found between the radiological pattern of ILD and the types of disease-specific antibodies.Conclusion. The 6MWT data in conjunction with the results of testing for SSc-specific autoantibodies provide a very accurate prediction of the presence and extent of ILD. It is advisable to include these indicators in the algorithm for screening and monitoring patients with SSc.У пациентов с системной склеродермией (ССД) интерстициальное заболевание легких (ИЗЛ) является фактором снижения функциональной способности, вплоть до инвалидизации, а также основной причиной смерти. Поэтому одна из важнейших задач при ведении данной группы больных — не только выявление поражения дыхательной системы, но и прогнозирование вероятности его развития.Цель исследования — изучение возможности прогнозирования развития ИЗЛ и распространенного ИЗЛ у пациентов с ССД.Материал и методы. В исследование включено 79 больных ССД (средний возраст — 64,4±11,5 года; 94,9% — женщины) из Регистра миозитов, ССД и смешанного заболевания соединительной ткани (РЕМИССиС), которым была проведена компьютерная томография легких высокого разрешения (КТВР). Для прогнозирования развития распространенного ИЗЛ осуществлялось построение классификационных деревьев (КД) с помощью алгоритма CHAID (исчерпывающий). У всех пациентов проведено тестирование на антитела к Scl70 (анти-Scl70), CENP-B (анти-CENP-B), PmScl (анти-PmScl).Результаты и обсуждение. Признаки ИЗЛ по данным КТВР выявлены у 53 пациентов. Наиболее часто обнаруживались фибротический (34,2%) и клеточный (15,2%) типы неспецифической интерстициальной пневмонии, реже — обычная интерстициальная пневмония (11,4%). Наличие ИЗЛ и распространенного ИЗЛ (вовлечение более 20% паренхимы легких) значимо ассоциировалось с выявлением любых аутоантител, кроме антицентромерных, повышением систолического давления в легочной артерии, снижением форсированной жизненной емкости легких, диффузионной способности легких, насыщения крови кислородом в покое и всех показателей теста 6-минутной ходьбы (ТШХ), а также с жалобами на одышку. Кроме того, наличие распространенного ИЗЛ, также значимо было связано с диффузной формой ССД и с ССД без кожных проявлений.При построении КД установлено, что развитие распространенного ИЗЛ маловероятно у лиц, способных пройти более 440 м в ТШХ и не имеющих ни анти-Scl70, ни анти-PmScl.Обнаружены также значимые связи между рентгенологическим паттерном ИЗЛ и типами выявленных болезнь-специфических антител.Заключение. Данные ТШХ в сочетании с результатами исследования на специфические для ССД аутоантитела позволяют с высокой точностью прогнозировать наличие и распространенность ИЗЛ. Эти показатели целесообразно включить в алгоритм обследования и наблюдения пациентов с ССД