The influence of dispersion particles on the Portevin-Le Chatelier effect: from average particle characteristics to particle arrangement

The Portevin-Le Chatelier (PLC) effect in Al-Mg alloys reinforced with second-phase particles was studied both experimentally and by computer simulation. An emphasis is placed on the understanding of the influence of the arrangement, and not just the volume fraction and average spacing of particles, on plastic instability. Statistical properties of stress jumps, sensitive to the dynamical features of plastic instability, were analyzed alongside macroscopic characteristics of stress-strain curves. The analysis provides a quantitative basis for a comparison between the observed and the simulated behavior of materials with different particle populations. The computer model comprises several principal ingredients: (i) a local feature of the negative strain rate sensitivity of stress (ii) non-local effects stemming from plastic strain incompatibilities and accounted for by an elastic-type spatial coupling and (iii) the particle distribution included in the model with the aid of the Voronoi mesh technique. (C) 2004 Elsevier B.V. All fights reserved.