The influence of cooling rate on the microstructure of an Al–Ni hypereutectic alloy

An Al–4 at.% Ni alloy was prepared by a melt spinning technique and characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and high resolution transmission electron microscopy. The resulting ribbon microstructure consists of intermetallic Al9Ni2 globular-like structures embedded within an aluminum matrix. Characteristic globules are nanometric (∼ 100 nm) and are mainly located at the grain boundaries. The resulting effect on the mechanical properties is the enhancement of the alloy hardness from 58 to 371 HV.