Quantitative Studies on the Amorphization of Quasicrystals by Means of High Voltage Electron Microscopy

Abstract

The radiation‐induced phase transition from the quasicrystalline to the amorphous state is studied by means of highvoltage electron microscopy. The quasicrystalline phases in the investigated alloys, Al86Mn14, Al76Mn20Si4, Al80Mn16Ru4, Al86Mn7Fe7, and Mg32Al19Zn30 can all be amorphized under irradiation with 1 MeV electrons at temperatures between 20 and 30 K. Furthermore, the electron dose required for complete amorphization of the quasicrystals is determined in dependene of electron energy in Al86Mn14 and Mg32Al19Zn30 alloys and in dependence of irradiation temperature and orientation of the quasicrystals in the Al86Mn14 alloy. The results of investigations on are discussed the basis of the current structural models. It is concluded that a high degree of chemical order is a prerequisite for the stability of the quasicrystalline phases.

Formation of a stable decagonal quasicrystal in cobalt ion implanted aluminum

“…A binary Al-Co decagonal quasicrystal has formed after 100 keV Co ϩ -ion implantation into pure Al with a dose of 1.5ϫ10 17 ion/cm 2 , and the quasicrystal has shown a high thermal stability. The composition of stable decagonal quasicrystal is believed to be Al 11 Co 4 .…”

“…In fact, there have been many other types of phase transformation induced directly by ion irradiation. [16][17][18][19][20] In spite of the numerous studies undertaken, however, phase transformations in quasicrystals induced by ion implantation have only received minor attention. So far, there has been no stable quasicrystal formed by means of the ion implantation technique, especially in metal and alloy materials, in the literature.…”