Amorphization of Intermetallic Compounds by High Energy Electron Irradiation

1982年，这位首席研究员发现，在高压电子显微镜(HVEM)中，通过原位电子辐照可以在NiTi化合物中产生晶态到非晶态(C-A)的转变。为了考察金属间化合物中~lt；e^-&gt；辐照引起的C-A相变的共性，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)系金属间化合物)，并在160K用2 MeV&lt；e^-&gt；在3 MV的超高压电磁波中进行了辐照，并对C-A相变的存在或不存在进行了原位监测。取得的成果可概括为以下几点。在19个过渡金属化合物中，有14个化合物，分别是：&lt；Co_2Ti&gt；，&lt；CuTi_2&gt；，&lt；Cu_4Ti_3&gt；，&lt；Cu3Ti_2&t；，CuTi，CuZr，&lt；Cu_(10)Zr_7，&lt；，&lt；NiTi，&lt；NiTi_2&>t；和&lt；Zr_2Ni&>t；辐照后发生了C-A转变，而另外五个，即CoTi，&lt；Cr_2Ti&>，&lt；Cu4Ti&>，FeTi和&lt；Ni_3Ti&>t；2.在35个Al-T金属间化合物中，有16个化合物是非晶态的，另外19个化合物表现出很强的抗非晶化能力。这些观察表明，~lt；e^-&gt；辐照诱导的C-A相变在金属间化合物中具有广泛的共性。成为非晶态的金属间化合物具有一个共同的特征，即它们的化学成分几乎与相应的二元合金系统中传统的液/气相淬火方法所能制备的非晶态材料的成分范围相同。通过这个项目，很明显，金属间化合物中各组分的化学物种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.