A phenomenological microscopic view of chemical reactivity of nanocrystalline materials under shear

A phenomenological approach is presented to analyse the reaction kinetics and compare the efficiency of processes driven by mechanochemical and thermal activation. Solid phase systems as well as gas–solid processes are examined: the synthesis of equiatomic CoFe nanostructured solid solution, the hydrogen absorption by Mg2Ni alloy and the CO hydrogenation over supported CoFe powder catalyst. In spite of the low efficiency of the mechanical processing technique, related to the discontinuous treatment, however, when elementary impact events are taken into account, mechanically activated processes show remarkably higher conversion rate values than their thermal counterparts. Such result can be related to the occurrence of mechanochemical effects.