Micromechanical interaction in two-phase iron-copper polycrystals

The plastic deformation of two-phase iron-copper polycrystals was studied experimentally and modelled in a semi-analytical approach, taking into account work-hardening behaviour, initial texture, slip processes and volume fractions of the phases. Iron-copper polycrystals including the single-phase materials were produced by powder metallurgy in various compositions of iron and copper. The two-phase materials had microstructures ranging between interpenetrating networks and matrix/inclusion type. Samples were deformed by rolling and compression at room temperature. Besides stress vs. strain during compression the texture and the microhardness distribution were measured before and after the deformation. The determined quantities (stress, strain, texture) were compared with model calculations performed with a viscoplastic self- consistent (VPSC) model from R. Lebensohn and C. Tome. The best predictions of this model were found in the case of copper inclusions in an iron matrix whereas for interpenetrating networks a viscoplastic Taylor model was in better accordance with experiment. Compositions include Fe with 17, 33, 50, 67, and 83 vol. % Cu.