Amorphization of Intermetallic Compounds by High Energy Electron Irradiation

1982年，现任首席研究员发现，在高压电子显微镜（HVEM）下，原位电子辐照可以在NiTi化合物中产生晶体到非晶态（C-A）的转变。本项目为考察<e^->辐照诱导金属间化合物C-A跃迁的普遍性，制备了一系列金属间化合物（即19种过渡金属化合物和35种Al-T （T：过渡金属）体系金属间化合物），并在3mv UHVEM 160K下用2MeV <e^->辐照，现场监测了C-A跃迁的存在（或不存在）。所得结果可总结如下：1。19种过渡间金属化合物中，<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>、<Zr_2Ni>等14种化合物经辐照后发生C-A跃迁，其余5种化合物CoTi、<Cr_2Ti>、<Cu_4Ti>、FeTi、<Ni_3Ti>均保持结晶状态。在35种Al-T金属间化合物中，16种化合物呈现非晶态，其余19种化合物表现出较强的抗非晶态能力。这些观察结果表明，<e^->辐照引起的C-A跃迁是金属间化合物中普遍存在的现象。变为无定形的金属间化合物有一个共同的特点，即它们的化学成分几乎与在相应的二元合金体系中用传统的液相和/或气相淬火方法产生的无定形材料的成分范围相同。通过该项目可以明显看出，金属间化合物中成分的化学种类及其原子分数的组合在决定电子辐照过程中非晶相形成的趋势方面起着至关重要的作用。

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.