Properties of powder materials products are significantly defined by
their structural state whose formation depends on the production
conditions. Pressing powder under high pressures considerably changes
the conditions of its consolidation and is followed by a plastic
deformation of the material that essentially influences its structure
and properties. Additional superposition of shear strain with high
hydrostatic pressure still further facilitates the conditions for
powder consolidation as well as for obtaining materials with
fine-grained structure which provides a unique complex of properties.
In the work there was made the investigation at room temperature of
the effect of high hydrostatic pressure and deformation with a shear
at high pressures on the pressability, structure and properties of
molybdenum powders.
It was shown that with the growth of pressure an essential increase of
specimen density accompanied by growth of hardness (from 1.2 to 3.8
GPa) and X-ray line broading took place. The influence of shear
deformation became notisable at 0.5 GPa pressure.
On the base of the analysis of X-ray line broadning together with
metallografic investigation it was supposed that high pressure with
shear caused the formation of cellular dislocation structure at room
temperature, i.e. to obtaine large plastic deformation without
failure.
It can be expected that it would be most efficient to apply pressure
with shearing in the temperature region T>=T*, when optimal structural
states and increased mechanical properties are formed. Here T* is
characteristical temperature of deformation that was introduced by the
authors in previous investigations. For Mo T* is about 200C.
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