Effect of Cooling Rate on the Microstructure Evolution and Mechanical Properties of Iron-Rich Al–Si Alloy

Abstract

The mechanical properties of iron-rich Al–Si alloy is limited by the existence of plenty of the iron-rich phase (β-Al5FeSi), whose unfavorable morphology not only splits the matrix but also causes both stress concentration and interface mismatch with the Al matrix. The effect of the cooling rate on the tensile properties of Fe-rich Al–Si alloy was studied by the melt spinning method at different rotating speeds. At the traditional casting cooling rate of ~10 K/s, the size of the needle-like β-Al5FeSi phase is about 80 μm. In contrast, the size of the β-Al5FeSi phase is reduced to 500 nm and the morphology changes to a granular morphology with the high cooling rate of ~104 K/s. With the increase of the cooling rate, the morphology of the β-Al5FeSi phase is optimized, meanwhile the tensile properties of Fe-rich Al–Si alloy are greatly improved. The improved tensile properties of the Fe-rich Al-Si alloy is attributed to the combination of Fe-rich reinforced particles and the granular silicon phase provided by the high cooling rate of the melt spinning method.

The Fatal Defects in Cast Al-Si Alloys Due to Sn Addition

“…Besides the parameters of casting [7][8][9], compositions also strongly affect casting defects in Al-Si alloys. For example, the plate-like β-AlFeSi is always generated in Al-Si alloys with Fe addition, which increases porosity during solidification by blocking liquid feeding channels [10][11][12]. The addition of Mn can transform β-AlFeSi phases into Chinese script such as α-AlFeMnSi phases [11,[13][14][15], contributing to the reduction in porosity.…”

Development of Inoculants for Aluminum Alloy: A Review

“…However, the addition of these elements leads to a further increase in the content of the iron-rich phase, which makes them impossible to use without restriction [84,85]. In addition, the use of high cooling speed, ultrasonic treatment, friction stir processing, and other methods can limit the size of the iron-rich phase and can transform the iron-rich phase of the crystal type and improve the mechanical properties of the alloy [86][87][88]. As shown in Figure 6, the optical micrographs of Al-Si-Fe at different cooling rates show different stages of iron-rich phase [89].…”