The Preparation And Properties Of Quasicrystalline Mg-Zn-Y Alloys

In this article, we prepared Mg-Zn-Y system quasicrystal with various methods, and the compound of the alloys was designed as Mg₄₂Zn₅₀Y₈. The analysis results showed that bulk quasicrystal can be got at various cooling rates. The X-ray pattern showed that the main phases in the Mg₄₂Zn₅₀Y₈ alloys were icosohedral quasicrystallin phase and hypothermia phase. The component of the quasicrystal phase is approximately Mg₃₀Zn₆₀Y₁₀, and that of hypothermia phase is approximately Mg₇₀Zn₃₀. the icosohedral quasicrystallin phase exhibits irregular petal-like patterns and polygon-like patterns. Cooling rates have dramatic influence on the patterns of the icosohedral quasicrystal phase. The more rapid the cooling rate is the more slender the quasicrystal polygons are. Though the external conditions have great influence on the quasicrystal patterns the determinant factors of the quasicrystal pattern are its specific quasi-periodic structure. We can find its specific quintic symmetry though transmission electron microscope. Many quasicrystals can be prepared by quenching method, but the quenching method is not suitable for the formation of Mg₃₀Zn₆₀Y₁₀ quasicrystal. The phases generated through flash set method are Mg₁₀Y₂Zn crystalline phase and amorphous phase.The hydrogen absorption capacity of alloys is determined by the chemical reaction between hydrogen and alloys and the position and number of interstices that can contain hydrogen. The icosohedral quasicrystal just posses lots of tetrahedral interstices and possess Mg and Y elements that can react with hydrogen. So the icosohedral quasicrystal possesses the ability of hydrogen storage in theory. We carried out the hydrogen storage capacity test of the quasicrystal alloys by making it into negative electrodes of Ni-MH batteries. The test results showed that the alloys were not easy to be activated and posses very low discharge capacity. With the increase of temperature the discharge capacity enhanced dramatically but the cycle stability decreased at the same time. This has something to do with the high temperature needed for hydrogen absorption and release and poor corrosion resistance of Mg. We also do some research on the influence of the intensity of solutions on the alloy's hydrogen absorption.