Microstructure and mechanical behavior of ODS and non-ODS Fe-14Cr model alloys produced by spark plasma sintering

In this work the spark plasma sintering (SPS) technique has been explored as an alternative consolidation route for producing ultra-fine grained Fe–14Cr model alloys containing a dispersion of oxide nanoparti-cles. Elemental powders of Fe and Cr, and nanosized Y₂O₃ powder have been mechanically alloyed in a planetary ball mill and rapidly sintered in a spark plasma furnace. Two alloys, with nominal compositions Fe–14%Cr and Fe–14% Cr–0.3%Y₂O₃ (wt.%), have been fabricated and their microstructure and mechanical properties investigated. The results have been compared with those obtained for other powder metal-lurgy processed alloys of the same composition but consolidated by hot isostatic pressing. The SPS tech-nique under the present conditions has produced Fe–14Cr materials that apparently exhibit different microstructures yielding inferior mechanical properties than the counterpart material consolidated by hot isostatic pressing. Although the presence of a dispersion of Y-rich particles is evident, the oxide dis-persion strengthened (ODS) Fe–14Cr alloy consolidated by SPS exhibits poor tensile properties. The extensive decoration of the powder particle surfaces with Cr-rich precipitates and the residual porosity appear to be responsible for the impaired properties of this ODS alloy consolidated by SPS.This investigation was supported by the Ministry of Science and Innovation of Spain (Project No. ENE 2008-06403-C06-04), the Comunidad de Madrid through the program ESTRUMAT-CM(Grant No. S0505/MAT/0077), and the European Commission through the European Fusion Development Agreement (Contract No. 09-240), the IP3 FP6 ESTEEM project (Contract No. 026019) and the Fusion Energy Materials Science (FEMaS) FP7 coordination action.Publicad

Psychometric Study of “Questionnaire of Barriers Perceived” (QBP) in Higher Education

This article presents the process of adaptation and validation, and the resulting psychometric properties, of the “Questionnaire of Barriers Perceived” (QBP). The scale identifies whether a student’s perceptions and expectations are mediated by stereotypes or roles associated with gender through the study of their professional aspirations, fear of negative judgement, and perceptions/awareness of gender roles of men and women. Two descriptive studies were conducted via a cross-sectional poll. The questionnaire was administered first to 240 students and then to a total of 1044 student from all the degrees studied at the Faculty of Education at the university at which the study took place. The data were subjected to item content analysis, descriptive analysis, analysis of internal consistency, study of the relationship between variables, correlational analysis, and an exploratory and confirmatory factorial analysis. The results showed that the scale had a high goodness-of-fit index, as well as validity and reliability. The dimensions that the model comprised were found to be interrelated and coherent with the theoretical structure considered in the initial version of the instrument. The resulting questionnaire presented sufficient validity and reliability to be used in other contexts and studies of the same nature

Microstructure and tensile properties of oxide dispersion strengthened Fe–14Cr– 0.3Y₂O₃ and Fe–14Cr–2W–0.3Ti–0.3Y₂O₃

Proocedings of: 15th International Conference on Fusion Reactor Materials (ICFRM15). Charleston, South Carolina (United States of America), 16-22 october, 2011Two ODS ferritic steels with nominal compositions (wt.%): Fe–14Cr–0.3Y2O3 and Fe–14Cr–2W–0.3Ti–0.3Y2O3 have been produced by mechanical alloying and consolidation by hot isostatic pressing. The microstructure and tensile properties of these materials after being forged and heat treated at 1123 K have been investigated to clarify the interrelation between composition, microstructure and mechanical properties. The second phase precipitates in these alloys have been analyzed by high angle annular dark field imaging in scanning TEM mode and electron diffraction. Fe–14Cr–2W–0.3Ti–0.3Y2O3 exhibits a duplex microstructure consisting of large recrystallized grains, as large as 1.5 μm, and unrecovered regions containing submicron equiaxed grains. In addition, three types of secondary phase particles have been found: large M₂₃C₆ particles containing W and Cr, (Cr + Ti) rich spherical particles with diameters between 50 and 500 nm, and fine (Y + Ti) oxide particles with sizes below 30 nm. In contrast, Fe14CrY shows a uniform structure of equiaxed grains, with sizes in the range 0.5 3 μm, containing a fine disper sion of Y oxide particles (<30 nm) homogeneously distributed inside the grains, as well as large carbide and oxide particles. Tensile tests performed over the temperature range 273 973 K have revealed that the alloy containing W and Ti has lower yield and tensile strengths than Fe–14Cr–0.3Y2O3 at tempera tures up to 773 K, but the opposite appears to occur beyond this temperature.This investigation was supported by the Spanish Ministry of Science and Innovation (Project No. ENE 2008 06403 C06 04 and Juan de la Cierva program), the Comunidad de Madrid through the program ESTRUMAT CM (Grant S0505/MAT/0077), and the European Commission through the European Fusion Development Agreement (Contract No. 09 240), the IP3 FP6 ESTEEM project (Contract No. 026019) and the Fusion Energy Materials Science (FEMaS) FP7 coordination action.Publicad

Thermal conductivity and diffusivity of Cu-Y alloys produced by different powder metallurgy routes

Full density Cu-1%Y and Cu-0.8%Y alloys have been produced by different powder metallurgy routes and subsequent hot isostatic pressing. Some of the alloys have been subjected to equal channel angular pressing (ECAP) via BC route up to 8 passes. ECAP deformation homogenizes and refines the microstructure up to attaining a sub-micron grain structure. Thermal properties have been characterized by the laser flash method in the temperature range 373–773 K. The ECAP process, irrespective of the production route, enhanced the thermal conductivity to values similar to those for CuCrZr (ITER grade). The linear thermal expansion coefficient was temperature independent for all materials

Comportamiento mecánico en función de la temperatura de aleaciones wolfranio-vanadio

Libro de proceedings de: XI Congreso Nacional de Materiales, Zaragoza, 23 junio 2010En esta investigación se evalúa el comportamiento mecánico del wolframio puro y de dos de sus aleaciones con contenidos de 2% y 4% de vanadio, fabricadas mediante prensado isostático en caliente (HIP). La caracterización mecánica se ha realizado mediante ensayos de flexión en tres puntos en atmósfera oxidante a distintas temperaturas comprendidas entre temperatura ambiente y 1000 ºC. Adicionalmente, se han realizado ensayos en inmersión en nitrógeno líquido para los de -197 ºC. Estos últimos valores pueden servir para una determinación más precisa de la temperatura la transición dúctil-frágil en éstos materiales, y de su posible comportamiento plástico o frágil a temperatura ambiente. Mediante estos ensayos ha sido posible obtener la tenacidad de fractura, la resistencia mecánica, el límite elástico y el módulo de elasticidad en función de la temperatura. Así mismo, se ha determinado la densidad y la dureza Vickers para dos cargas distintas, lo que permitido determinar la influencia de este parámetro en la medida realizada. Adicionalmente, se han examinado mediante microscopia electrónica de barrido las superficies de fractura. De esta forma ha sido posible determinar el modo de rotura y analizar la relación de las propiedades mecánicas macroscópicas con los micromecanismos de fallo involucrados.Este trabajo ha sido financiado por EFDA/CIEMAT WP08-09-MAT-WWALLOY, Ministerio de Ciencia e Innovación, MAT2007-29278-E, BIA2004-04835, y MAT2009- 13979-C03-02, y Comunidad de Madrid, SS2009/MAT-1585 y S2009/ENE-1679Publicad

The materials production and processing facility at the Spanish National Centre for fusion technologies (TechnoFusión)

Proceedings of : The 26th Symposium of Fusion Technology (SOFT-26), Porto (Portugal),- 27 september - 1 october 2010.In response to the urgent request from the EU Fusion Program, a new facility (TechnoFusion) for research and development of fusion materials has been planned with support from the Regional Government of Madrid and the Ministry of Science and Innovation of Spain. TechnoFusion, the National Centre for Fusion Technologies, aims screening different technologies relevant for ITER and DEMO environments while promoting the contribution of international companies and research groups into the Fusion Programme. For this purpose, the centre will be provided with a large number of unique facilities for the manufacture, testing (a triple-beam multi-ion irradiation, a plasma-wall interaction device, a remote handling for under ionizing radiation testing) and analysis of critical fusion materials. Particularly, the objectives, semi-industrial scale capabilities and present status of the TechnoFusion Materials Production and Processing (MPP) facility are presented. Previous studies revealed that the MPP facility will be a very promising infrastructure for the development of new materials and prototypes demanded by the fusion technology and therefore some of them will be here briefly summarized.This work has been supported by Madrid Community through the project TECHNOFUSION (S2009/ENE/1679).Publicad

Microstructural characterization of Y₂O₃ ODS-Fe-Cr model alloys

Proceedings of the: Thirteenth International Conference on Fusion Reactor Materials. Nice (France), 10-14/12/2007.Two Fe-12 wt% Cr alloys, one containing 0.4 wt% Y₂O₃ and the other Y₂O₃ free, have been produced by mechanical alloying followed by hot isostatic pressing. These oxide dispersion strengthened and reference alloys were characterized both in the as-HIPed state and after tempering by transmission electron microscopy and atom-probe tomography. The as-HIPed alloys exhibited the characteristic microstructure of lath martensite and contained a high density of dislocations. Small voids with sizes <10 nm were also observed. Both alloys also contained M₃C and M₂₃C₆ carbides (M = Cr, Fe) probably as a result of C ingress during milling. After tempering at 1023 K for 4 h the microstructures had partially recovered. In the recovered regions, martensite laths were replaced by equiaxed grains in which M₂₃C₆ carbides decorated the grain boundaries. In the ODS alloy nanoparticles containing Y were commonly observed within grains, although they were also present at grain boundaries and adjacent to large carbides.This research has been supported by FP6 Euratom Research and Training Programme on Nuclear Energy. The financial support from the Comunidad de Madrid, through the program ESTRUMAT CM,Grant S 0505/MAT/0077.Publicad

Microstructure and mechanical properties of ultrafine-grained Fe─14Cr and ODS Fe─14Cr model alloys

This study is to: The 14th International Conference on Fusion Reactor Materials (ICFRM-14) was held at the Sapporo Convention Center in Sapporo, Japan from 7 to 12 September 2009Reduced activation ferritic Fe─14 wt%Cr and Fe─14 wt%Cr─0.3 wt%Y₂O₃ alloys were produced by mechanical alloying and hot isostatic pressing followed by forging and heat treating. The alloy containing Y₂O₃ developed a submicron-grained structure with homogeneous dispersion of oxide nanoparticles that enhanced the tensile properties in comparison to the Y₂O₃ free alloy. Strengthening induced by the Y₂O₃ dispersion appears to be effective up to 873 K, at least. A uniform distribution of Cr-rich precipitates, stable upon a heat treatment at 1123 K for 2 h, was also found in both alloys.This investigation was supported by the Spanish Ministry of Science and Innovation (project No ENE 2008-06403-C06-04 and Juan de la Cierva program), the Comunidad de Madrid through the program ESTRUMAT-CM (grant S0505/MAT/0077), and the European Commission through the European Fusion Development Agreement (contract No. 09-240), the IP3 FP6 ESTEEM project (contract No. 026019) and the Fusion Energy Materials Science (FEMaS) FP7 coordination action.Publicad

Liver injury in non-alcoholic fatty liver disease is associated with urea cycle enzyme dysregulation

The main aim was to evaluate changes in urea cycle enzymes in NAFLD patients and in two preclinical animal models mimicking this entity. Seventeen liver specimens from NAFLD patients were included for immunohistochemistry and gene expression analyses. Three-hundred-and-eighty-two biopsy-proven NAFLD patients were genotyped for rs1047891, a functional variant located in carbamoyl phosphate synthetase-1 (CPS1) gene. Two preclinical models were employed to analyse CPS1 by immunohistochemistry, a choline deficient high-fat diet model (CDA-HFD) and a high fat diet LDLr knockout model (LDLr −/−). A significant downregulation in mRNA was observed in CPS1 and ornithine transcarbamylase (OTC1) in simple steatosis and NASH-fibrosis patients versus controls. Further, age, obesity (BMI > 30 kg/m2), diabetes mellitus and ALT werefound to be risk factors whereas A-allele from CPS1 was a protective factor from liver fibrosis. CPS1 hepatic expression was diminished in parallel with the increase of fibrosis, and its levels reverted up to normality after changing diet in CDA-HFD mice. In conclusion, liver fibrosis and steatosis were associated with a reduction in both gene and protein expression patterns of mitochondrial urea cycle enzymes. A-allele from a variant on CPS1 may protect from fibrosis development. CPS1 expression is restored in a preclinical model when the main trigger of the liver damage disappears

The Diet of Diabetic Patients in Spain in 2008–2010: Accordance with the Main Dietary Recommendations—A Cross-Sectional Study

Background: No previous study has assessed the diet of the diabetic patients in the general population of an entire country in Europe. This study evaluates accordance of the diet of diabetic adults in Spain with nutritional recommendations of the European Association for the Study of Diabetes (EASD), American Diabetes Association (ADA), and the Mediterranean diet (MD). Methods and Findings: Cross-sectional study conducted in 2008-2010 among 12,948 persons representative of the population aged ≥18 years in Spain. Usual food consumption was assessed with a dietary history. EASD accordance was defined as ≥6 points on a score of 12 nutritional goals, ADA accordance as ≥3 points on a score of 6 goals, and MD accordance as ≥7 points on the Mediterranean Diet Adherence Screener. In the 609 diagnosed diabetic individuals, the diet was rich in saturated fat (11.2% of total energy), but trans fat intake was relatively low (1.1% energy) and monounsaturated fat intake was high (16.1% energy). Carbohydrate intake was relatively low (41.1% energy), but sugar intake was high (16.9% energy). Intake of cholesterol (322 mg/day) and sodium (3.1 g/day) was also high, while fiber intake was insufficient (23.8 g/day). EASD accordance was observed in 48.7% diabetic patients, ADA accordance in 46.3%, and MD accordance in 57.4%. The frequency of EASD, ADA and MD accordance was not statistically different between diagnosed and undiagnosed diabetic individuals. Conclusions: Only about half of diabetic patients in Spain have a diet that is consistent with the major dietary recommendations. The lack of dietary differences between diagnosed and undiagnosed diabetic individuals reflects deficiencies in diabetes managementThe ENRICA study is funded by Sanofi-Aventis. Additional funding is obtained from FIS grant PI09/1626 and from the ‘Cátedra UAM de Epidemiología y Control del Riesgo Cardiovascular