Refining and modification effects of (Al, Zr, Si)–Al4Sr on Al–7Si–0.5 Mg alloy

Abstract

The Al–9Zr-0.9Sr master alloy was used to refine and modify the Al–7Si-0.5 Mg alloy, and to improve the refining and modification effects, the Al–9Zr-0.9Sr master alloy was carried out melt spinning treatment. The second phase particles in the ribbon are smaller and more evenly distributed than those in the ingot. The Al–Zr–Sr inoculation showed excellent refining and modification effects on Al–7Si-0.5 Mg alloy, and in the range of 1 wt.%∼4 wt.%, the refining effect was gradually enhanced with the increase of the inoculant dosage. The morphology and size of particles in inoculant have significant effects on the refinement and modification effects of the inoculant. The X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and selected area electron diffraction (SAED) results showed that in Al–7Si-0.5 Mg matrix alloy, (Al, Zr, Si) instead of Al3Zr was used as the heterogeneous nucleation substrate of α-Al to refine the grains. The Sr element in the master alloy was mainly used to modify eutectic silicon, and melt spinning could effectively improve its modification effect on eutectic silicon. With the increase of inoculant dosage, the mechanical properties of the alloy were gradually improved. However, when the dosage was increased to 4 wt.%, some large rod-like particles appear due to the excessive Zr element, resulting in a decrease in elongation.