Browsing by Keyword "microstructure"
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Item Fracture analysis of the transition zone between unreinforced alloy and composite(1993-10) Goñi, J.; Muñoz, A.; Viviente, J. L.; Liceaga, J. F.; Centros PRE-FUSION TECNALIA - (FORMER); TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThe transition zone between unreinforced alloy and composite is an important problem for selectively reinforced metal-matrix composites manufactured by the squeeze casting technique, mainly because of the weakness of this zone. Developing an understanding of transition zone behaviour is therefore essential. The main purpose of this research was to evaluate the influence of ageing time on the fracture behaviour of such a zone for Saffil (γ-alumina) A356 aluminium alloy composites. Tensile tests were carried out and the fracture surfaces were analysed to evaluate the fracture behaviour. Analysis of microstructure and fracture surfaces was performed using optical and scanning electron microscopies.Item Lamellar Spacing Modelling for LPBF Aluminum Parts(2022-12) Anglada, Eva; García, José Carlos; Arrue, Mario; Cearsolo, Xabier; Garmendia, Iñaki; CIRMETALThe high cooling rates reached during metal additive manufacturing (MAM) generate microstructures very different from those obtained by other conventional manufacturing methods. Therefore, research about the modeling of this type of microstructure is of great interest to the MAM community. In this work, the prediction of the lamellar spacing of an AlSi10Mg sample manufactured by laser powder bed fusion (LPBF), is presented. A multiscale approach is used, combining a CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) model to predict the material properties, with a macroscale model of the sample manufacturing and with a microscale model to predict the microstructure. The manufacturing and metallographic characterization of the sample is also included. The results prove that the multiscale strategy followed is a valid approximation to simulate this type of manufacturing process. In addition, it is shown that the use of a generic simulation software focused on metal casting processes can be useful in predicting the lamellar spacing of the microstructure manufactured by LPBF. Finally, the relationship between the cooling rate and the resulting lamellar spacing has been established for this AlSi10Mg under the specific manufacturing conditions considered.Item Metal-diamond materials obtained by electric resistance sintering: microstructure, processing and mechanical properties(European Powder Metallurgy Association (EPMA), 2021) Lagos, M. A.; Viñuela, J.; Leizaola, I.; Agote, I.; Beranoagirre, A.; EXTREMATMetal-diamond tools are well established in the mining sector for the cutting of granite, marble and others. To date, the manufacturing process of diamond tools consists of at least two main steps (cold pressing and sintering by hot pressing or furnace sintering). This process takes several hours. This work presents the fabrication of metal-diamond tools by a very fast process, Electric Resistance Sintering. This method permits the pressing and densification of the pieces in few seconds and without protective atmosphere. This work presents the effect of the processing parameters on the microstructure and mechanical properties of the materials. The characterization of the products includes the microstructural analysis and hardness. It was possible to obtain good densification of the compacts and mechanical properties showed interesting results. Two different compositions were used. One of them was based in cobalt-diamond, a very well-known material for metal-diamond tools. In addition, another composition based in Fe-Cu-Ni was also tested.Item Understanding the effect of MPEG-PCE's microstructure on the adsorption and hydration of OPC(2023-04) Emaldi, Iñaki; Erkizia, Edurne; Leiza, Jose Ramon; Dolado, Jorge S.; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNPolycarboxylic ethers or polycarboxylate (PCEs) are one of the most employed superplasticizers in construction. However, the understanding of their microstructure–property relationship is still incomplete. Recently, a theoretical model was proposed that relates the microstructure–conformation of the PCE to its effect on the adsorption onto cement particles and cement hydration time. In this work, the effects of a wide range of PCEs with different side chain lengths (P = 5, Group 1; P = 20, Group 2; and P = 45 and 113, Group 3) having flexible backbone worm conformation except one which has stretch backbone worm conformation (P = 113) were experimentally investigated for their effect on adsorption and cement hydration. It is found that PCEs from Group 1 show electrostatic repulsion as dispersing mechanism, unlike PCEs from Groups 2 and 3. Furthermore, the prediction of the theoretical model is also assessed for all the studied PCEs. Only Group 1 PCEs (shortest side chains) showed deviation from the theoretical predictions, and it was attributed to their different behaviors from the standard PCEs for which the theoretical model was developed.