High-resolution electron microscopy of nanocrystalline Ni-Al alloys: instability of ordered structure and dynamic behaviour of grain boundaries
High-resolution electron microscopy of nanocrystalline Ni-Al alloys: instability of ordered structure and dynamic behaviour of grain boundaries
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纳米晶镍铝合金的高分辨率电子显微镜：有序结构的不稳定性和晶界的动态行为
DOI：
10.1007/bf00349953
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发表时间：
1994
影响因子：
4.5
通讯作者：
N. Tanaka
中科院分区：
文献类型：
--
作者：
T. Kizuka;N. Mitarai;N. Tanaka
用高分辨电子显微镜对真空沉积的纳米晶镍铝化物薄膜进行了研究。在沉积的薄膜中观察到了几种镍铝化物有序结构，即L12(Ni3Al)-、B2(NiAl)-、D513(Ni2Al3)-和D020(NiAl3)型结构。随着晶粒度的减小，L12和B2有序结构变得不稳定。在室温下，L12和B2型有序结构向无序结构转变的临界晶粒度约为5 nm。具有L12和B2型结构的纳米晶Ni-Al薄膜具有较高的原子扩散能力和足够的晶粒长大能力，并且在400℃以上有序度增加。在强电子辐照下，在原子分辨率下动态观察了室温下具有L12型结构的Ni-Al纳米晶之间的扩散连接过程。结果表明，即使在常温下，纳米晶的旋转和滑动也不会产生裂纹，而且颈缩仍在继续。
High-resolution transmission electron microscopy was performed on vacuum-deposited nanocrystalline nickel aluminide films. Several nickel aluminide ordered structures, i.e. L12(Ni3Al)-, B2(NiAl)-, D513(Ni2Al3)- and D020(NiAl3)-type structures, were observed in the deposited films. The L12and B2 ordered structures became unstable with decreasing grain sizes. The critical grain size on transformation from the L12- and B2-type ordered structures into disordered structures was ca. 5 nm at ambient temperatures. High atomic diffusion, sufficient for grain growth, and an increase in the ordering occurred just above 400°C in the nanocrystalline Ni-Al films with L12- and B2-type structures. The diffusion bonding process, at ambient temperatures, between Ni-Al nanocrystallites with an L12-type structure was observed dynamically at atomic resolution under strong electron irradiation. It was found that the nanocrystallites rotated and slid without crack generation, and neck-growth proceeded even at ambient temperatures.