Amorphization of Intermetallic Compounds by High Energy Electron Irradiation

点击翻译按钮获取中文摘要

In 1982, the present head-investigator found that a crystalline to amorphous (C-A) transition could be produced in a NiTi compound by in-situ electron irradiation in a high voltage electron microscope (HVEM). In this project, in order to examine the generality of the <e^-> irradiation induced C-A transition in intermetallic compounds, a series of intermetallics (i.e., 19 kinds of intertransition metal compounds and 35 kinds of Al-T (T:transition metals) system intermetallic compounds) were prepared and all irradiated with 2MeV <e^-> in a 3 MV UHVEM at 160K, and the presence (or absence) of the C-A transition was monitored in-situ. Results obtained can be summarized as follows.1. Of the 19 intertransition metal compounds, 14 compounds, i.e., <Co_2Ti> , <CuTi_2> , <Cu_4Ti_3> , <Cu_3Ti_2> , CuTi, CuZr, <Cu_(10)Zr_7> , <Fe_2Ti> , <Mn_2Ti> , MoNi, <Nb_7Ni_6> , NiTi, <NiTi_2> , and <Zr_2Ni> , proved to undergo a C-A transition upon irradiation, while the other five, i.e., CoTi, <Cr_2Ti> , <Cu_4Ti> , FeTi, and <Ni_3Ti> , remained crystalline.2. Of the 35 Al-T intermetallic compounds, 16 compounds were rendered amorphous, while the other nineteen showed stout resistance against amorphization.3. These observations indicate that the <e^-> irradiation induced C-A transition is a phenomenon of wide generality in intermetallic compounds.4. The intermetallic compounds that become amorphous have a common feature that their chemical compositions are almost identical with the compositional ranges over which amorphous materials can be produced by the conventional liquid- and/or vapor-phase quenching method in the corresponding binary alloy systems.5. It becomes evident through this project that the combination of chemical species of the constituents and their atomic fractions in the intermetallic compound play an essential role in determining the tendency toward amorphous phase formation during electron irradiation.