Quasicrystals of the Al–Cu–Fe system have attracted considerable attention due to their unique physical and mechanical properties, such as high hardness, low friction coefficient, and good corrosion resistance. However, their limited plasticity prevents their widespread use in structural materials. One promising way to increase the plasticity of quasicrystals is dispersion strengthening by introducing soft, plastic particles into the matrix. This study examines the effect of Sn particles on the strengthening and mechanical properties of Al–Cu–Fe(-B) quasicrystals.
The effect of small Sn additives on the mechanical properties of cast quasicrystalline Al–Cu–Fe(-B) composite materials at room temperature was studied. For this purpose, compression and three-point bending tests were performed on notched samples. Microstructure analysis revealed a linear relationship between the Sn particle size in the cast composites and their volume fraction. The introduction of approximately 10% Sn by volume made it possible to double the tensile strength of cast Al–Cu–Fe alloys and triple the fracture resistance of cast Al–Cu–Fe–B alloys. The improvement in strength properties is due to mechanisms that prevent the formation and propagation of microcracks, as well as to the filling of cracks in cast composites with a quasicrystalline matrix with Sn particles of different sizes.
The composite materials were produced by mechanical alloying of Al, Cu, Fe, Sn and, in some cases, B powders. The resulting powder mixtures were consolidated by hot pressing. Microstructural studies were performed using scanning and transmission electron microscopy. Mechanical properties were assessed using microhardness measurements and compression tests.
The results showed that the introduction of Sn particles leads to the formation of a dispersion-hardened microstructure, in which Sn particles are uniformly distributed in the quasi-crystalline matrix. The addition of Sn helps to increase the plasticity of composite materials without a significant decrease in hardness. The introduction of boron (B) into the alloy composition additionally helps to refine the structure and increase strength. The results obtained demonstrate the promise of using Sn particles to improve the mechanical properties of Al–Cu–Fe(-B) quasicrystals and expand their areas of application.
Author: Eric Fleury, Yu-Chan Kim, Do-Hyung Kim, Do-Hyang Kim, Won-Tae Kim
Institute:
Yonsei University, Center for Non-Crystalline Materials, 134, Shincheon-dong, Seodaemin-gu, Seoul 120-749, South Korea
Faculty of Applied Sciences, Jeonju University, Jeonju 360-764, South Korea