Crystallisation of amorphous Al-Sm-Ni-(Cu) alloys

Abstract

The primary crystallisation and intermetallics formation of an amorphous Al 88–Sm4 -Ni 8 alloy has been studied. The effect of 1 at% Cu substituting Al or Ni is also considered. The initial microstructure of the melt-spun ribbons is studied by X-ray diffraction. Differential scanning calorimetry shows that the thermal stability of the amorphous alloy is affected by Cu, increasing when Cu substitutes Al and decreasing when substituting Ni. Transmission electron microscopy shows that Cu reduces the size of the initial nanocrystals. After the high-temperature stages of crystallisation, the developed structure is analysed in detail by combining X-rays diffraction, differential scanning calorimetry and transmission electron microscopy. The study includes the effect of Cu on the appearance sequence and characteristics of the intermetallics up to 600 °C. Cu retards the appearance of the stable Al 19 Sm3 Ni5 phase, with an acicular shape being more easily developed.