The Microstructure and Mechanical Properties of Hyper Eutectic Al-Si Alloy during Hot Extrusion Process

摘要

In this paper, the process parameters of hot extrusion of the hyper eutectic Al-Si alloy that has been dealtrnby electromagnetic stirring are studied. The results indicated, the ultimate tensile strength of the alloy reaches 229.5 MPa,rnthe Elongation reaches 4. 6% after extruded with extrusion ratio 10. Compared with extruded with extrusion ratio 20, thernultimate tensile strength reaches 263.2 Mpa, the elongation reaches 5.4% , which indicates that the mechanical properties isrnobviously promoted. Primary Si phase, eutectic Si, Mg_2Si,Al-Si-Ni-Cu-La-Ce and Al-Si-Mn-Fe-Cr-Mo phases become fine atrnsome different degrees after hot extruded, and the degrees of refinement is increased with extrusion ratio improved. After T6rnheat treatment, the sharp corners of these phases become passivity, their surface is more rounder, and the mechanicalrnproperties is enhanced even more, the ultimate tensile strength of the alloy reaches 335. 3 MPa after extruded with extrusionrnratio 10. And it is increased to 353.6 MPa after extruded with extrusion ratio 20, however, the elongations is decreased arnlittle.