|About this Abstract
||MS&T23: Materials Science & Technology
||Recent Developments in Light-Weight Composites and Materials
||Strengthening Mechanisms of Ultrasonically Refined A356 (Al-Si-Mg) Aluminum Alloy
||Katherine Rader, Aashish Rohatgi
|On-Site Speaker (Planned)
Ultrasound applied to aluminum during solidification within a mold is capable of refining the local microstructure without the need for grain-refiners or post-casting processing. The resulting microstructure is stronger and more ductile than the dendritic microstructure of un-sonicated material. This study will discuss the strengthening mechanisms in an A356 aluminum alloy (Al-Si-Mg) with 0.91 wt.% Fe cast with local ultrasonic intensification. Ultrasound transformed the morphology of β-Al5FeSi particles from needle-shaped to rectangular, reducing their strength concentration effects. Ultrasound also transformed the morphology of the primary aluminum grains from dendritic to globular. Because the size of the globular grains was similar to the SDAS of the un-sonicated material, YS was unaffected. However, because the globular microstructure could accommodate more plastic deformation than the dendritic microstructure, elongation increased. UTS also increased as ductility increased. These ultrasound-induced improvements in microstructure and mechanical properties can potentially enable the greater use of secondary aluminum alloys.