Heterogeneous nucleation of icosahedral phase from FCC phase in cast Al₈₇Mn₄Si₂Be₇alloy

The formation of the icosahedral (i) quasicrystalline phase has been studied in the cast Al87Mn4Si2Be7 alloy. Under low cooling rates, i-phase particles of about 5 to 15 µm formed in the αAl matrix. A thorough examination of the microstructure revealed the existence of cubic crystalline phases embedded in the i-particles. Microstructural and thermal analyses indicated that the i-particles nucleated heterogeneously from the cubic AlMn(Si)Be4 phases by a peritectic reaction, however with a slight misorientation.