Nanostructure formation by mechanical attrition

Mechanical attrition by high energy ball milling has been developed as a versatile alternative to other processing routes including vapor evaporation, liquid quenching and chemical synthesis methods. In this process, lattice defects are produced by ''pumping'' energy into initially single-crystalline powder particles of typically 50 mu m particle diameter The internal refining process with a reduction of the average grain size by a factor of 10(3) - 10(4) results from the creation and self-organization of dislocation cell networks, small-angle grain boundaries and finally high-angle grain boundaries within the powder particles during the milling process. As a result, increases in atomic level internal strains excess enthalpy, excess specific hear and Vickers hardness are observed far beyond the levels obtained during conventional deformation processes.