On the Impact of Texture and Grain Size on the Pseudoelastic Properties of Polycrystalline Fe–Ni–Co–Al–Ti Alloy

The effects of thermomechanical treatments on crystallographic texture and grain size evolution and their impact on the pseudoelastic properties in Fe41–Ni28–Co17–Al11.5–Ti2.5 (at.%) were studied in the present paper. The results show that cold rolling leads to brass-type texture in this alloy, which is typical for low stacking fault energy materials. Thermal treatments up to 1300 °C were conducted and it is shown that the presence of β-phase helps to control grain growth. After the dissolution of the secondary phase induced by heat treatment at higher temperatures, a strong {230}〈001〉 recrystallization texture evolves in cold rolled samples already upon imposing medium reduction ratios. Finally, good pseudoelastic properties are found in conditions being characterized by adequate texture and grain sizes spanning over the entire thickness of the samples tested.Fil: Sobrero, Cesar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Lauhoff, C.. University of Kassel; AlemaniaFil: Wegener, T.. University of Kassel; AlemaniaFil: Niendorf, T.. University of Kassel; AlemaniaFil: Krooß, P.. University of Kassel; Alemani

Grain size effect on the thermal-induced martensitic transformation in polycrystalline Cu-based shape memory alloys

In Cu-based SMA alloys, the grain size (d) effect on the martensitic transformation temperature was investigated for a wide range of d. Specimens were prepared by different heat treatments in order to create a range of grain sizes, from about 500 nm (ribbons and tapes obtained by rapid solidification techniques) up to 6 mm diameter single-crystals (grown by the Bridgman method). Information obtained from the literature was also included in the set of analyzed experimental data. The reduction of grain size shifts the forward transformation temperature downwards. These grain-size effects are observed in specimens with d below ∼ 100 μm, and become more pronounced for d below ∼ 20 μm. An empirical expression was obtained that describes the grain-size effect over the whole temperature range. The obtained curve differs considerably from the Hall-Petch behaviour reported in the literature by some other investigators.Fil: la Roca, Paulo Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; ArgentinaFil: Isola, Lucio Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; ArgentinaFil: Sobrero, Cesar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; ArgentinaFil: Vermaut, P.. Ecole Nationale Superieure de Chimie de Paris; FranciaFil: Malarria, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; Argentin

Crystallographic orientation relationships in the α→γ′ martensitic transformation in an Fe-Mn-Al-Ni system

The Fe43.5Mn34Al15Ni7.5 (at.%) alloy exhibits outstanding pseudoelastic behaviour over a wide range of temperatures. This alloy undergoes an unusual martensitic transformation from a disordered body-centred cubic (α) parent phase to a face-centred cubic γ′) product phase. In the present work, the orientations of the parent and product phases for quenched samples were analysed by electron backscatter diffraction. Bain, Kurdjumow-Sachs, Pitsch, Nishiyama-Wassermann and Greninger-Troiano orientation relationships between the parent and product phases were compared with experimental results. The Pitsch relationship appears to be the most suitable to describe the α→γ′ martensitic transformation. This result provides experimental support to the dislocation-based heterogeneous Bogers-Burgers type transformation mechanism. No indications of variant selection were detected in the thermally activated transformations.Fil: Vallejos, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Sobrero, Cesar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Avalos, Martina Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Signorelli, Javier Walter. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Malarria, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentin

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Excellent pseudoelasticity of Al-rich Fe–33Mn–17Al–6Ni–0.15C (at%) shape memory single crystals obtained without an aging conditioning stage

The pseudoelastic behavior of a series of Fe?33Mn?17Al?6Ni?0.15C (at%) shape memory alloy single crys- tals was analysed with compression tests. The specimens, with different crystallographic orientations, showed almost 100% strain recovery after a full stress-induced martensitic transformation. The size and distribution of precipitates introduced in the alloy processing proved to be clearly suitable for achieving a completely reversible pseudoelastic transformation, without the need of additional aging in this Al-rich alloy. The transformation strain was analysed using the phenomenological theory of martensite transfor- mation. This model roughly describes the pseudoelastic strain under compression as a function of the crystallographic orientation.Fil: Vallejos, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; ArgentinaFil: Giordana, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Sobrero, Cesar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; ArgentinaFil: Malarria, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; Argentin

Estudio microestructural y de texturas en aleación Fe43.5Mn34Al15Ni7.5 con memoria de forma

La aleación Fe43.5Mn34Al15Ni7.5, descubierta recientemente, presenta comportamiento pseudoelástico en un amplio rango de temperaturas. Esta característica resulta atractiva para aplicaciones automovilísticas, espaciales, criogénicas y sísmicas. En la actualidad no existe un análisis exhaustivo de las distintas fases que pueden generarse en la aleación con los tratamientos térmicos y de la influencia de las texturas sobre las propiedades de memoria de forma. El material estudiado fue laminado en caliente a una temperatura de 1000ºC y luego tratado térmicamente a diferentes temperaturas a fin de analizar las fases presentes, su microestructura y sus orientaciones cristalinas. Se determinó que la fase martensítica γ se logra con temples desde temperaturas superiores a los 1200°C. Además, bajo tratamientos térmicos por encima de 1000°C se obtienen tamaños de grano en la fase α cercanos al mm, resultando a priori en una mejora de las propiedades pseudoelásticas de la aleación.Fe alloy 43.5Mn34Al15Ni7.5 recently discovered, has pseudoplastic behavior in a wide temperature range. This characteristic is attractive for automobile, space, cryogenic and seismic applications. Currently there is no comprehensive analysis of the phases generated by heat treatments in the alloy and the influence of textures in shape memory properties. generated in the alloy with heat treatment and the influence of the textures on the properties of shape memory. The material studied was hot rolled at a temperature of 1000 ° C and then heat treated at different temperatures in order to analyse the phases present, microstructure and crystal orientations. The studies show that the martensitic phase (γ) is achieved with quenching in water at temperatures over 1200ºC. Furthermore, heat treatments above 1000ºC generate grain sizes in α phase close to a millimeter. This grains growth would improve pseudoelastic properties of the alloy.Fil: Vallejos, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Sobrero, Cesar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: la Roca, Paulo Matías. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Malarria, Jorge Alberto. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Física de Metales; Argentin

Cyclic Superelastic Behavior of Iron-Based Fe-Ni-Co-Al-Ti-Nb Shape Memory Alloy

Iron-based shape memory alloys came into focus as promising candidate materials for large-scale structural applications owing to their cost-efficiency. In the present work, the superelastic properties of a recently introduced Fe-Ni-Co-Al-Ti-Nb shape memory alloy are investigated. For 〈001〉-oriented single-crystalline material in aged condition (650 °C/6 h), an incremental strain test reveals excellent superelasticity at −130 °C with fully reversible strains up to about 6%. Under cycling loading at different test temperatures, however, the alloy system investigated suffers limited functional stability.Fil: Lauhoff, C.. University of Kassel; AlemaniaFil: Remich, V.. University of Kassel; AlemaniaFil: Giordana, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Sobrero, Cesar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Niendorf, T.. University of Kassel; AlemaniaFil: Krooß, P.. University of Kassel; Alemani

Influence of Pearlite Formation on the Ductility Response of Commercial Hadfield Steel

This manuscript presents the singular event of pearlite occurrence in commercially produced Hadfield steel. A detailed characterization of the microstructure is performed and its influence on the mechanical properties of the material is analyzed. The found microstructure may be interpreted as carbide formation if observed at the optical microscope. However, it consists of an extremely fine lamellae structure ranging from 40 to 130 nm of thickness. Experimental evidence of pearlite formation is supported by microhardness measurements, X-ray diffraction and secondary electron microscopy. The pearlite is located on the austenitic grain boundaries and within by means of intragranular islands. The occurrence of this phase is detrimental for the ductility response of the material assessed by means of uniaxial tensile testing and reduction of area determination. It is observed that a pearlite fraction of 20 % is responsible for a reduction of 90 % in elongation at fracture and a drop of 80 % in reduction of area. A short heat treatment performed at 1050°C allows recovering the ductility response of the material keeping grain size and chemical composition unchanged.Fil: Martín, Mauro Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Raposo, Marcio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Druker, Ana Velia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Sobrero, Cesar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Malarria, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentin

Multifilamentary MgB2 Wires Prepared by an In Situ Powder-in-Tube Method

MgB2 has become a commercially attractive material for technological applications for its particular superconducting properties. However, due to its brittleness to obtainwires, a metallic sheath is needed for drawing. In the presentwork, grade 2 titanium has been used as sheath material, and several multifilamentary wires have been prepared. The powder-in-tube method has been used to prepare the wires with the in situ variant, where the sheath is filled with the unreacted precursor powders (Mg and B). Different thermal treatments have been investigated including several intermediate treatments during the drawing process in addition to the final one. This last treatment is necessary to accomplish the synthesis and heal the cracks generated during the cold work. The superconducting properties were determined by magnetization measurements on a SQUID magnetometer, and the microstructure evolution was followed by TEM and SEM microscopy. Mechanical behavior is also evaluated.Fil: Sobrero, Cesar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Vallejos, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Nordeste. Facultad de Ingeniería; ArgentinaFil: San Martin, Victor Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Malachevsky, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Serquis, Adriana Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentin

Nanoprecipitation effects on phase stability of Fe-Mn-Al-Ni alloys

Early stages of coherent precipitation have been studied in several Fe-Mn-Al-Ni samples aged at 200 °C for different time intervals in order to analyze the effect of nanoprecipitation on the phase stability during thermally induced martensitic transformations. The α-γ′ martensitic transformation was studied by means of dilatometry measurements. Transmission electron microscopy (TEM) observations were performed in order to characterize the microstructure of the samples. The size and volume fraction of nanoprecipitates were evaluated for the as-quenched material and samples aged for 10, 20 and 180 min. Considering these data and additional high resolution TEM results reported in the literature a phenomenological model is presented that enables understanding the effects of B2 precipitates on the relative phase stability between austenite and martensite, and their influence on the observed pseudoelasticity of this metallic system. With this model, the changes of the measured transformation temperatures can be predicted with considerable accuracy.Fil: la Roca, Paulo Matías. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Baruj, Alberto Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Sobrero, Cesar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Malarria, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Sade Lichtmann, Marcos Leonel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentin