Structure and Mechanical Properties of Powdered Quasicrystalline Al94Fe3Cr3 Alloy Consolidated by Quasi-Hydrostatic Compression

Abstract

Background. Quasicrystalline Al-based alloys belong to the class of the state-of-the-art metal materials for the application in light engineering constructions, primarily in aviation and the motor transport industry. These materials are commonly made in the form of powders, which is due to the high productivity of powder metallurgy methods. Therefore, the powder consolidation methods are of great importance in the production of products, which is associated with certain difficulties, and consequently, they should be chosen considering not only the quasicrystals’ propensity to brittle fracture but also the metastable nature of the quasicrystalline phases. Certain possibilities in this direction are provided by the quasi-hydrostatic compression method, which can provide a non-trivial combination of strength and ductility properties of materials. Objective. The aim of the paper is to investigate the effect of high pressure under quasi-hydrostatic compression on the formation of structure, phase composition and mechanical properties of the quasicrystalline Al 94 Fe 3 Cr 3 alloy. Methods. 40 μm Al 94 Fe 3 Cr 3 alloy quasicrystalline powder was fabricated by water-atomisation technique. Consolidation of quasicrystalline powder was performed by quasi-hydrostatic compression technique in high-pressure cells at room temperature at a pressure of 2.5, 4, and 6 hPa. Structure, phase composition and mechanical characteristics of Al 94 Fe 3 Cr 3 alloy were performed by scanning electron microscopy (SEM), X-ray diffraction andmicromechanical tests. Results. Using the phase X-ray analysis and SEM, the content of the quasicrystalline icosahedral phase (i-phase) in the Al 94 Fe 3 Cr 3 alloy structure was completely preserved after its consolidation at different pressures (2.5, 4, and 6 hPa) under quasi-hydrostatic compression at room temperature. Despite the high pressure applied in the consolidation process, the morphology of quasicrystalline phase particles located in the a-Al deformed matrix solid solution remains unchanged. The mechanical properties of the alloy exceed the similar characteristics of the alloy consolidated by warm extrusion. Conclusions. Consolidation of the Al 94 Fe 3 Cr 3 alloy powder under quasi-hydrostatic compression allows for the complete conservation of metastable quasicrystalline i-phase particles in the aluminum matrix, which provides the highest values of strength properties together with sufficient ductility for application in the engineering practice.