It is demonstrated that controlled highhyphen;strainhyphen;rate plastic deformation of heterogeneous reactive porous materials (Nb+Si, Mo+Si+MoSi2) produces shear localization. Within the shear bands, having thicknesses 5ndash;20 mgr;m, the overall strains (ggr;le;100) and strain rates (ggr;dot;le;107sminus;1) result in changes in particle morphology, melting, and regions of partial reaction. The shear band thickness is smaller than the initial characteristic particle size of the porous mixture (le;44 mgr;m). This ensures quenching of the deformed material structure in the same time scale as the deformation time (10minus;5s). In the shear localization region, two types of patterning are observed: (a) a characteristic shear fracture which subdivides the Nb particles into thin parallel layers and (b) the formation of vortices. copy;1994 American Institute of Physics.
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