Interfacial Reactions Between Al7075 Alloy and BaAl₂Si₂O₈ + CaAl₂Si₂O₈ Mixture

The present work reports the SEM, EPMA and TEM examination of reactions at the interface of Al7075 alloy and a 50/50 wt% mixture of BaAl₂Si₂O₈ + CaAl₂Si₂O₈ feldspars at 850 °C, 1150 °C and 1250 °C. Sintering of the feldspar mixture at 1450 °C caused dissolution of ~1.0 wt% Ca in BaAl₂Si₂O₈ and 0.5 wt% Ba in CaAl₂Si₂O₈. The interaction of the Al alloy with the sintered feldspars shifted the alloy composition to the Al–Si–αBaAl₂Si₂ and Al–Si–βaAl₂Si₂ compatibility triangles. The feldspars underwent a series of phase transformations, leading ultimately to the formation of Al₂O₃.