| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1617516 | Journal of Alloys and Compounds | 2011 | 5 Pages |
The properties of nanostructured A357 ribbons produced by melt spinning were investigated using field emission gun scanning electron microscope, X-ray diffraction pattern, differential scanning calorimetry and microhardness testing in comparison with those fabricated by direct-chill (DC) casting. The solidification time and cooling rate of 46 μm thick melt-spun ribbon were estimated to be 9.13 × 10−6 s and 1.17 × 107 K s−1, respectively. The results show that the nanostructure of A357 ribbons exhibits the enhanced solid-solubility of Si in Al matrix to 2.00 wt.% and the existence of ultra-fine and homogenous dendritic structure having a dendrite arm spacing of about 200 nm. The nano-sized spherical eutectic Si crystals having a size of 50 nm were also observed. All these structural factors increase the microhardness of the ribbon which is twice as high as that of DC casting.
► The solidification time and the cooling rate of 46 μm thick melt-spun ribbon were estimated to be 9.13 × 10−6 s and 1.17 × 107 K s−1, respectively. ► A solid-solubility extension value of 2.00 wt.% Si in Al was determined for A357 alloy ribbon. ► The dendrite arm spacing reduced from about 17 μm in case of DC cast to about 200 nm in case of melt spinning. The nano-sized spherically shaped eutectic Si 50 nm in size was formatted by melt spinning and the grain size of melt-spun ribbon was about 92.0 nm. ► The microhardness value of melt-spun A357 alloy is twice as much as that of the DC cast ingot.
