The study of strengthening mechanisms in aluminum-based alloys containing nanoscale quasicrystalline (NQC) inclusions is an important task in modern materials science. Combining the light weight of aluminum with the high strength and hardness of quasicrystals, it is possible to create materials with a unique set of properties that are promising for applications in the aerospace and automotive industries. In particular, the Al-Fe-Cr-Ti alloy containing an icosahedral phase is of considerable interest due to its potential for strengthening through various mechanisms.
The main strengthening mechanism is dispersion strengthening caused by the interaction of dislocations with NCC particles. The passage of dislocations through the matrix is hindered by the need to bend around solid NCC inclusions, which leads to an increase in the yield strength and strength of the alloy. The effectiveness of dispersion strengthening depends on the size, shape, distribution and volume fraction of NCC particles.
In addition, strengthening may be associated with the development of coherent stresses around the NCC particles, caused by the difference in thermal expansion coefficients between the matrix and inclusions. These stresses may interact with dislocations, hindering their movement and promoting strengthening. An additional factor is the formation of a solid solution, when atoms of alloying elements such as Fe, Cr and Ti dissolve in the aluminum matrix, causing distortions of the crystal lattice and hindering the movement of dislocations.
Innovative aluminum alloys with nano-dispersed inclusions demonstrate outstanding mechanical properties, significantly outperforming traditional aluminum alloys. This makes them promising for use in the automotive and aerospace industries. In particular, aluminum alloys with a nano-quasi-crystalline structure obtained by rapid crystallization have shown excellent tensile strength and high specific strength.
However, their application is limited by temperature instability during operation and thermomechanical processing, as well as variability of properties depending on the production method. Galano et al. showed that the introduction of alloying elements such as Ti, V, Nb or Ta increases the thermal stability of the icosahedral phase in melt-spinned Al-Fe-Cr alloys.
In composites containing the Al-Fe-Cr-Ti NCC phase, strengthening is also possible due to the redistribution of stresses between the matrix and the strengthening phase. The creation of an optimal microstructure characterized by a uniform distribution of NCC particles with controlled sizes and shapes is key to achieving the maximum strengthening effect.
Author: S. Pedrazzini, M. Galano, F. Audebert, D. M. Collins, F. Hofmann, B. Abbey, A. M. Korsunsky, M. Lieblich, A. Garcia Escorial, G. D. W. Smith
Institute: Department of Materials Science, University of Oxford, Parkes Road, Oxford OX1 3PH, UK, INTECIN, Faculty of Engineering, University of Buenos Aires, Paseo Colon, 850, Buenos Aires, Argentina, Department of Engineering and Mathematical Sciences, Oxford Brookes University, Wheatley Campus, OX33 1HX, Oxford, UK, Faculty of Engineering and Technology, University of Oxford, Parkes Road, Oxford OX1 3PJ, UK, ARC Centre of Excellence in Molecular Imaging, La Trobe University, Victoria 3086, Australia, Department of Physical Metallurgy, CENIM-CSIC, Avenida Gregorio del Amo, 8, Madrid, Spain