Title screen

[References: 8 tit.]

The recently suggested statistical theory of flow stress, including yield strength, for polycrystalline materials under quasi-static plastic deformation is developed in the framework of a two-phase model. Analytic and graphic forms of the generalized Hall-Petch relations are obtained for samples with BCC ([alpha]-phase Fe), FCC (Cu, Al, Ni) and HCP ([alpha]-Ti, Zr) crystalline lattices at T=300 K with different values of grain-boundary (second) phase. The maximum of yield strength and respective extremal grain size of the samples are shifted by changing of the second phase. Temperature dependence in the range of 100-350 K for yield strength (using the example of Al) revealed its increase for closely packed nanocrystalline samples with the growth of temperature. An enlargement of the second phase in a sample neutralizes this property