Effect of Si on Fe-rich intermetallic formation and mechanical properties of heattreated Al-Cu-Mn-Fe alloys

摘要

The effect of Si on Fe-rich intermetallics formation and mechanicalproperties of heat-treated squeeze cast Al-5.0Cu-0.6Mn-0.7Fe alloy wasinvestigated. Our results show that increasing Si content promotes theformation of Al15(FeMn)3(SiCu)2 (${\alpha}$-Fe), and varying the morphology ofT (Al20Cu3Mn2) where the size decreases and the amount increases. The majorreason is that Si promotes heterogeneous nucleation of the intermetallicsleading to finer precipitates. Si addition significantly enhances ultimatetensile strength and yield strength of the alloys. The strengthening effect ismainly owing to the dispersoid strengthening by increasing volume fraction of Tphase and less harmful ${\alpha}$-Fe with a compact structure, which make thecracks more difficult to initiate and propagation during tensile test. Thesqueeze cast Al-5.0Cu-0.6Mn-0.7Fe alloy with 1.1% Si shows significantlyimproved mechanical properties than the alloy without Si addition, which hastensile strength of 386 MPa, yield strength of 280 MPa and elongation of 8.6%.