氩离子轰击感生Ni_2Al_3和NiAl_3成分变化的TEM/EDS研究

A TEM/EDS INVESTIGATION ON RADIATION-INDUCED COMPOSITION CHANGES OF Ni_2Al_3 AND NiAl_3 UNDER BOMBARDMENT WITH Ar^+ IONS

在能量为3,5和7 keV的氩离子轰击下,对激冷Ni-50％Al(质量分数)合金薄膜进行减薄,用配备有超薄窗口能谱仪的高分辨电镜观察分析了减薄后样品中两种合金相Ni2Al3和NiAl3的结构和成分变化.结果表明,在离子轰击下,合金相Ni2Al3和NiAl3的成分均有变化,Ni含量明显高于合金相化学配比.随着离子能量的降低,轰击后合金相中Ni含量增加.在3 keV氩离子轰击下两个相的含Ni量均高达87％(原子分数)左右,在离子轰击过程中初始的NiAl3相点阵结构未发生明显变化,而Ni2Al3的初始结构在3和5 keV氩离子轰击减薄后部分转变为体心立方结构.

A rapidly solidified Ni-50%Al (mass fraction)alloy ribbon mainly consisting of Ni2Al3 and NiAl3 phases was Ar+ ion etched with energies of 3, 5 and 7 keV respectively and the specimens were examined by high resolution electron microscopy (HREM) with super-thin-window EDS. The results show that under 3-7 keV Ar+ ion bombardment, the compositions of both Ni2Al3 and NiAl3 change greatly and the Ni concentration is much higher than the corresponding stoichiometric one. With decreasing the ion energy the content of Ni in the phases increases. After 3 keV Ar+ ion bombardment the contents of Ni in these two phases are nearly the same, about 87% (atomic fraction), the original crystal structure of NiAl3 phase is kept, while the structure of Ni2Al3 phase changes partly to a bcc structure.