Phase transformations under ball-milling

It is possible to predict which phase stabilises as a function of the milling conditions? Two systematic experimental studies of phase transformations under ball milling (crystal to amorphous transition in NixZry and order-disorder in FeAl) have demonstrated that the end product of a milling treatment and the associated path depends on the milling temperature and intensity (to be defined in the text). A simple model for the competition between shear induced disorder and thermally activated atom jumps yields a dynamical equilibrium phase diagram for FeAl under milling in good agreement with experimental findings. Atomistic Monte Carlo simulations of an ordered compound under sustained shearing reproduces most behaviors observed in FeAl;moreover the achieved microstructure is found to depend on the amplitude and geometry of the disorder introduced by each shearing event, as well as on the number of vacancies produced by non conservative dislocation motions. Advantage is taken from the above results for practical purposes. An example is given of optimizing the milling treatment for synthesizing nanocomposite materials for electrical applications.