Quasicrystals, which have a unique combination of aperiodic long-range order and forbidden crystallographic symmetry, are of considerable interest as promising functional materials. However, their application is limited by their fragility and the difficulty of obtaining dense bulk samples. Powder sintering is one of the key methods for obtaining dense quasicrystalline materials.
In this paper, we investigate the sintering processes of quasicrystalline Al-Cu-Fe powder using two advanced methods: spark plasma sintering (SPS) and hot pressing (HP). SPS, due to rapid heating and application of pulsed current, provides effective compaction in a short time, minimizing grain growth and undesirable phase transformations. HP, in turn, allows achieving high density due to the simultaneous application of pressure and temperature.
The investigations of the compaction of granulated quasicrystalline AlCuFeB powder by transmission electron microscopy were carried out by means of hot pressing (HP) and spark plasma sintering (SPS). By combining the analysis of the sintering law (derived from the creep strain rate equations) and comparative studies of almost entirely dense sintered samples, mainly using microprobe analysis, hypotheses were formulated about the mechanisms at work. Regardless of the choice of the sintering method – SPS or HP – the existence of two regimes is assumed, the distinction between which is determined by whether the grain boundaries act as ideal sources/sinks of vacancies or not.
Experimental studies included optimization of sintering parameters for both methods. The influence of temperature, pressure and holding time on the density, microstructure and mechanical properties of the obtained samples were analyzed. The results showed that SPS provides higher density and preservation of the quasi-crystalline structure compared to HP at optimal parameters. Microstructure analysis revealed that SPS leads to the formation of a more homogeneous structure with a smaller grain size. The obtained results indicate the prospects of using SPS for obtaining dense and high-quality quasi-crystalline materials for various applications.
Author: Laure Ramond, Guillaume Bernard-Granger, Ahmed Addad, Christian Guizard
Institute: Laboratoire de Synthe`se et Fonctionnalisation des Ce´ramiques, UMR 3080 CNRS/Saint-Gobain, Saint-Gobain CREE, 84306 Cavaillon Cedex, France, Unite’ Mate’riaux et Transformations, UMR 8207 CNRS, Universite’ des Sciences et Technologies de Lille 1, 59655 Villeneuve d’Ascq Cedex, France