A study of nanocrystalline cobalt prepared by ball milling
  The hcp-fcc transformation induced in cobalt powder by ball milling at room temperature was studied using the excess Gibbs free energy for the metals, in nanometric form, to calculate the activation energy that the atoms need for the phase transformation to occur. The crystalline component of the nanocrystalline cobalt produced in our laboratory, via ball milling, was analized using the radial distribution function technique. The results suggest that the crystalline component has the same structure as the bulk, contradicting results already reported. 
J. C. de Lima, V. H. F. dos Santos, T. A. Grandi and R. S. de Biasi