Browsing by Keyword "Reactive sintering"
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Item Elemental powder metallurgy of TiAl alloys by spark plasma sintering(European Powder Metallurgy Association (EPMA), 2012) Lagos, M. A.; Agote, I.; EXTREMATDue to their density and mechanical properties TiAl-based alloys are very interesting materials for aerospace applications. Spark plasma sintering (SPS) is found to compact powders satisfactorily through the simultaneous application of direct current pulses of high intensity and pressure. Some works have studied the sintering of TiAl by means of SPS and it is believed that it is possible to obtain very fine microstructures and very interesting mechanical properties. As raw materials, normally pre-alloyed powders have been used, obtained by atomization or mechanical alloying. However, few works have studied the consolidation of elemental powders. This work presents the synthesis and densification of TiAl-based alloys by means of Spark Plasma Sintering (SPS) using elemental powders as raw materials. The selected composition was Ti-48Al-2Cr-2Nb. The evolution of the microstructure with the temperature is presented and in addition the diffusion of the elements (including heavy metals Cr and Nb) is studied.Item Fabrication of TiAl alloys by alternative powder methods(Minerals, Metals and Materials Society, 2014) Lagos, M. A.; Agote, I.; San Juan, J. M.; Hennicke, J.; Kim, Young-Won; Smarsly, Wilfried; Lin, Junpin; Dimiduk, Dennis M.; Appel, Fritz; EXTREMATUntil now TiAl alloys have been produced using a variety of processing methods including forging, extrusion, casting, etc. One important problem is the variation in mechanical properties caused by the segregation in the composition. In order to improve these segregations, powder metallurgy is an interesting alternative for the processing of TiAl alloys. However, some drawbacks of PM have limited the practical application of TiAl alloys such as the costs of the pre-alloyed raw materials, the use of expensive processing methods like HIP, etc. This work presents the activities performed at Tecnalia in the development of novel cost effective PM processing routes. Processes like Spark Plasma Sintering and Combustion Synthesis will be presented. Microstructures, crystallographic phases, chemical analysis and mechanical properties (tensile and creep) of the different processing routes will be detailed. Main advantages of these methods are the short processing time and the possibility of using elemental powders.Item Synthesis and densification of TiAl alloys by spark plasma sintering(European Powder Metallurgy Association (EPMA), 2011) Lagos, M. A.; Agote, I.; EXTREMATDue to their density and mechanical properties TiAl-based alloys are very interesting materials for aerospace applications and one of the most promising manufacturing routes for their fabrication is powder metallurgy. This work presents the synthesis and densification of TiAl-based alloys by means of Spark Plasma Sintering (SPS). The selected composition was Ti-48Al-2Cr-2Nb. Elemental powders as well as pre-alloyed powders were used in the process and the densification mechanism in both cases is explained. The main characteristics of the processes are presented and also the characterization of the obtained products.