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21

Jun 2017

Microstructural study of Co-based superalloys and ODS steels obtained by Spark Plasma Sintering (SPS)

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The CINN has collaborated with IMDEA Materiales and the University Carlos III in the microstructural study of Co-based superalloys and ferritic ODS steels consolidated by Spark Plasma Sintering. The results of these studies were presented as oral presentations in the VI edition of the National Congress of Pulvimetallurgy that took place in Ciudad Real (Spain) from 7th to 9th June 2017.

The abstracts of the two lectures given are shown below:

Microstructural study of a group 4 (Y-Al-Ti-Zr) ODS ferritic steel consolidated by Spark Plasma Sintering (SPS).

E.Macía1, J.Cornide1, A-García-Junceda2, L.A. Díaz3, M. Campos1.

1 UNIVERSIDAD CARLOS III

2 IMDEA Materiales

3 CENTRO DE INVESTIGACIÓN EN NANOMATERIALES Y NANOTECNOLOGIA (CINN)

Oxide Dispersion Strengthened (ODS) ferritic Steels are extraordinary candidates for nuclear applications due to their good behavior at high temperature and under irradiation conditions .ODS ferritic steel was produced by mechanical alloying and SPS to obtain a complex nanostructure. A four group elements (Y-Ti-Al-Zr) was selected to improve the stability of the precipitates since they are the main responsible for the thermal stability of fine structure. The heterogeneous distribution of stored energy due to the high energy attrition of MA powder will produce an inhomogeneous recrystallization during the consolidation step. After SPS consolidation a heterogeneous grain size distribution was attained, as recrystallization depends on the plastic deformation degree, on the composition of each particle and on the oxide dispersion promoted. Therefore sintering cycle was performed at 1373 K following fast heating rates (from 100 to 600 °C/min) to minimize porosity. The final microstructures were characterized by XRD and electron microscopy (SEM and TEM). In addition, Vickers microhardness and tensile tests was performed to analyze the mechanical response at R.T.

Microstructural study of Co-9Al-9W alloys produced by SPS with Ti and Ta as alloying elementsEstudio microestructural de aleaciones de Co-9Al-9W producidas por SPS con Ti y Ta como aleantes

Marta Cartón-Cordero1 , Mónica Campos2 , Eric Macia-Rodríguez2 , Luis Antonio Díaz, 3 Jesús Cano-Cabello2 , Andrea García-Junceda1 , José M. Torralba2

1 IMDEA Materiales

2 UNIVERSIDAD CARLOS III

3 CENTRO DE INVESTIGACIÓN EN NANOMATERIALES Y NANOTECNOLOGIA

Co-based superalloys with ϒ-ϒ dual phase microstructure are considered a good alternative for high temperature in extreme environmental conditions applications due to their good strength, wear behavior and high oxidation resistance. In this work a fully prealloyed gas atomized powder with the nominal composition of Co-9Al-9W (at%) has been used. With the aim of promoting the ϒ´ phase precipitate, 2 at% of Ti and 2 at% of Ta have been added through mechanical alloying to the original powder. In order to reach a high level of densification maintaining an ultrafine grain size in the microstructure, the powder has been consolidated through Spark Plasma Sintering (SPS). The ϒ´ phase precipitate is obtained after subsequent heat treatments, first a solution treatment and then aging. By X ray diffraction (XRD) technique and scanning and transmission electron microscopy (SEM/TEM), the structural and microstructural changes produced after the heat treatments from the as obtained material have been monitored. The addition of Ti and Ta to the base alloy improves the ϒ’ phase precipitation process, and also affect to its thermal stability, improving the high temperature performance of the alloy. To characterize this influence on the ϒ´solution temperature, a thermo-gravimetric analysis has been performed for different compositions and heat treatments.

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28

Nov 2016

Mechanics, Resource and Diagnostics of Materials and Structures (MRDMS-2016)

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The results of an international research on Zirconia-Graphene Nanocomposites was presented in the frame of the conference “Mechanics, Resource and Diagnostics of Materials and Structures (MRDMS-2016)” that took place in Ekaterinburg, Russia. The work was entitled “Black zirconia-graphene nanocomposite produced by spark plasma sintering” and was undertaken by scientists from the Moscow State University of Technology “STANKIN” and the CINN.

The research team success to fabricate theoretical dense electroconductive poreless black zirconia compacts by adding a small fraction of graphene oxide. This new functionality (electrical-thermal conductivity) enables the use of Spark Plasma Sintering (SPS) avoiding the limitations derived from the low thermal conductivity of zirconia and also allows the machining of complex-shaped components by electro-discharge machining methods (EDM).

For further information read the full paper.

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28

Nov 2016

Specifics of Wear of Ceramic Cutting Tool Inserts Featuring Al2O3-TiC Dies when Face Milling Hardened Cast Iron

Posted by / in Blog Industry, Latest CINN Publications, Publications 2016, Publications Multifunctional Nanocomposites 2016, Publications: Multifunctional Nanomaterials & Nanocomposites / No comments yet

This work studies wear kinetics of index able inserts (II) made of mixed ceramics based on Russian-manufactured in case of fine milling of special hardened cast iron with globular graphite. In a wide range of cutting parameters typical for fine milling, an impact of tool insert wearing parameters on qualitative and quantitative characteristics of the cutting process have been studied. Morphological traits and nature of wear of work surfaces has been studied using optical and scanning electron microscopy. Criteria of II states, as well as specifics of contact work surface transformation, correlating with force parameters of the face milling process, have been determined.

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