Precipitation during recrystallization in aluminum alloys with a small amount of iron and silicon
Precipitation during recrystallization in aluminum alloys with a small amount of iron and silicon
复制标题
含少量铁和硅的铝合金再结晶过程中的析出
DOI：
10.2464/jilm.20.137
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发表时间：
1970
期刊：
影响因子：
--
通讯作者：
I. Miki
中科院分区：
文献类型：
--
作者：
K. Nagahama;I. Miki
众所周知，少量的铁，通常作为杂质存在于商品铝及其合金中，对再结晶后的晶粒尺寸和团聚组织有很大的影响。然而，其机制仍未得到解决。铁原子在铝中的自扩散活化能由作者之一Miki估计为38.1±0.5 kcal/mol。该值相对高于铝或铝中的铜。铁原子在铝中的扩散、析出等行为的迟滞性和铁化合物的稳定性可以用上述事实来解释。根据平野等人的说法。在一定条件下，铁原子有可能通过位错进行管道扩散。然后，通过变形提高铝基体中的位错密度有望加速铁化合物的析出。本文通过硬度和电阻率的测定以及电子显微镜对薄膜的直接观察，研究了变形过饱和铝基体在恢复和再结晶过程中铁化合物的析出。所用合金为Al-0.043wt%Fe和Al-0.043wt%Fe-0.056wt%Si。结果表明：1)冷加工加速了铁化合物的析出，其析出速率与冷加工程度成正比。这种加速在再结晶初期尤为明显，在成核和长大过程中都有发生。2)观察到再结晶过程的阻滞。这可能是由于在再结晶初期在边界内形成的沉淀对亚边界的钉住作用所致。3)电镜观察了再结晶过程中形成的铁化合物的析出物，经衍射图鉴定为Al3Fe。这种情况下的沉淀物呈球状，与未变形的样品所观察到的完全不同。它们的分布不均匀，大小可分为两类。较大的（0.5 μ m）被认为是在亚晶界或晶界内成核。较小的（小于0.1μ）应在位错线上成核。
It is well known that a small amount of iron, usually contained in commercial aluminum and its alloy as an impurity, has great effects on grain size and aggregate structure after recrystallization. However, its mechanism remains still unsolved.The activation energy of self-diffusion of the iron atom in aluminum was estimated to be 38.1±0.5 kcal/mol by one of the authors1) (Miki). The value was comparatively higher than that of aluminum or copper in aluminum. The sluggishness of the behavior of the iron atom such as diffusion and precipitation in aluminum and the stability of iron compounds were explained by the above fact.According to Hirano et al2)., iron atom is likely to diffused through dislocations by pipe diffusion under certain conditions. Then, the precipitation of iron compound is expected to be accelerated by the increase of dislocation density in aluminum matrix by means of deformation.The object of this study was to examine the precipitation of iron compound from deformed super-saturated aluminum matrix during recovery and recrystallization by means of hardness and electric resistivity measurements and by direct observation of thin films by an electron mircoscope. The alloys used were Al-0.043wt%Fe and Al-0.043wt%Fe-0.056wt%Si.The results obtained are summarized as follows:1) Precipitation of iron compound was accelerated by cold working and its rate was proportional to the degree of cold working. The acceleration was especially evident at the early stage of recrystallization process, and it occurred in the both processes of nucleation and crystal growth.2) Retardation of the recrystallization process was observed. It would be attributed to the pinning of subboundaries by the precipitates, which were formed within the boundaries at the early stage of recrystallization.3) The precipitates of iron compound, which had been formed during the recrystallization, was observed by an electron microscope, and were identified as Al3Fe by diffraction patterns. The precipitates in this case were in globular form, quite different from those observed in undeformed specimens. They were not homogeneously distributed and their sizes were classified into two groups. The larger ones (0.5several microns) were supposed to be nucleated within subboundaries or grain boundaries. The smaller ones (less than 0.1μ) were supposed to be nucleated on dislocation lines.