The Effect of Free Volume on the Crystallization of Al87Ni8Gd5 Amorphous Alloy

The effect of free volume on the process of crystallization of an Al87Ni8Gd5 amorphous alloy is investigated. The deformation of the amorphous alloys leads to the formation of shear bands, which contain an enhanced free volume concentration. To retain the free volume the amorphous alloy was coated with a layer of a refractory metal. The structure of the Al87Ni8Gd5 alloy with a protective Ta coating was studied by X-ray diffraction and transmission electron microscopy methods. The fraction of the nanocrystalline phase formed in the amorphous samples with a protective Ta coating under annealing was found to be larger than that in the uncoated samples. The size of Al nanocrystals formed in the coated and uncoated samples is the same. A higher rate of crystal nucleation in the deformed amorphous samples with a protective coating is caused by a higher diffusion coefficient due to an enhanced free volume concentration.

Automated summary

The effect of free volume on the crystallization process of an Al87Ni8Gd5 amorphous alloy has been investigated. It was found that the deformation of the amorphous alloy leads to the formation of shear bands, which contain an enhanced concentration of free volume. To retain this free volume, a refractory metal was coated on the surface of the amorphous alloy. X-ray diffraction and transmission electron microscopy methods were used to study the structure of the Al87Ni8Gd5 alloy with a protective Ta coating. It was found that the fraction of nanocrystalline phase formed in the amorphous samples with the protective coating was larger than that in the uncoated samples. The size of Al nanocrystals formed in both coated and uncoated samples was the same. The higher rate of crystal nucleation in the deformed amorphous samples with a protective coating is attributed to a higher diffusion coefficient resulting from an enhanced concentration of free volume.