Thermal stability of nanocrystalline Al-5at.%Ni and Al-5at.%V alloys produced by high-energy ball milling

Nanocrystalline Al-5at.%V and Al-5at.%Ni alloys, prepared by high-energy ball milling and subsequent consolidation under uniaxial pressure of 3 GPa, were subjected to isothermal heat treatment for one hour at various temperatures-ranging from 100 to 614 °C. Grain growth, solid solubility of the alloying elements, and formation of additional phases following heat treatment were investigated using X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDXS). Vickers hardness was measured after heat treatment and correlated with the heat treatment temperature, composition, and microstructure. The heat treatment temperature and alloying element had a strong influence on hardness. The Influence of heat treatment on the microstructure and hardness of the alloys was dependent upon the diffusion coefficients of the alloying elements in Al.