Study of the Al-Si-X system by different cooling rates and heat treatment

Abstract

The solidification behavior of the Al-12.6% Si (A1), the hypereutectic Al-20%Si (A2) and the Al-20%Si-1.5% Fe-0.5%Mn (A3) (in wt. (%)) alloys, at different cooling rates is reported and discussed. The cooling rates ranged between 0.93 °C/s and 190 °C/s when cast in sand and copper wedge-shaped molds, respectively. A spheroidization heat treatment was carried out to the alloys in the as-cast condition at 540 °C for 11 hours and quench in water with a subsequent heat treatment at 170 °C for 5 hours with the purpose of improving the mechanical properties. The samples were characterized by optical microscopy, scanning electron microscopy and mechanically by tensile test, in order to evaluate the response of the heat treatment on the different starting microstructures and mechanical properties. It was found that alloys cooled at rates greater than 10.8 °C/s had a smaller particle size and better distribution, also showed a greater response to spheroidization heat treatment of all silicon (Si) phases. The spheroidization heat treatment caused an increase in the ultimate tensile stress (UTS) and elongation when compared with the alloys in the as-cast condition. The highest UTS value of 174 MPa was obtained for the (A1) alloy.

Effect of Rapid Solidification and Addition of Cu3P on the Mechanical Properties of Hypereutectic Al-Si Alloys

“…On the other hand, the minimum UTS (180 ± 2.5 MPa) and elongation (3.4%) values were obtained in the Al-20Si-1.5Fe-0.7Mn alloy. The mechanical properties obtained in this study are higher than the results reported in a previous work 16 . The increase of the UTS and the elongation (%) values could be attributed to the refinement of the primary Si due to combined effect of rapid solidification and the addition of the phosphorous compound.…”

Microstructural Evolution of Rapid Solidified Al-Ni Alloys

“…As it has been reported, the mechanical properties of pure aluminum can be improved when small amounts of second phases with high elastic modulus (similar to those used in composite materials) are formed by the addition of copper, silicon, nickel and other elements (i.e. Al 2 Cu, Al 3 Ni, Al 3 Ti, Al 13 Fe 4 ) [1][2][3][4][5][6][7][8].…”

A Continuous Casting Device with Electromagnetic Stirring for Production of SSM Feedstock Using Al-Si Alloys

“…Furthermore, heat transfer between ingot, mould and environment should be sufficient to prevent excessive grain growth and allow a sufficiently thick, solid shell to form and the mushy zone (where solid and liquid coexist in the solidifying ingot) to develop a substantial coherent volume, i.e., a solid matrix substantial enough to bear the extraction load [42][43][44] . Application of a conductive coating (e.g., graphite) or use of a highly conductive alloy as mould material could help to accelerate solidification 45,46 .…”