Interfacial reaction between Al₇₂Ni₁₂Co₁₆ decagonal quasicrystalline particles and liquid aluminium

The interfacial reaction between Al₇₂Ni₁₂Co ₁₆ quasicrystalline particles and pure Al melt at 670 °C was investigated. For all the studied samples, only one interfacial reaction product was detected at the interface by scanning electron microscopy. The product was identified to be the Al₉(Co, Ni)₂ crystalline phase, which show an rod-like morphology. The growth rate of the Al₉(Co, Ni) ₂ phase layer is very fast. Based on the microstructure analysis results, it is proposed that the layer growth is initially towards the liquid phase, but changes direction towards the quasicrystalline phase by the solid state reaction of diffusional Al with the quasicrystalline phase at the Al ₇₂Ni₁₂Co₁₆/Al₉(Co, Ni)₂ interface. A grain boundary grooving effect is deduced to have been involved during the reaction process.