The Enhanced Kinetics of Precipitation Effects in Ultra Fine Grained Mg Alloys Prepared by High Pressure Torsion

Abstract:

Precipitation effects in ultra fine grained (UFG) lightweight Mg-based alloys were studied in the present work by means of positron lifetime spectroscopy, transmission electron microscopy, and microhardness. The UFG samples with grain size around 100 nm were fabricated by high pressure torsion (HPT). The UFG structure contains a significant volume fraction of grain boundaries and exhibits a high number of lattice defects (mainly dislocations) introduced by severe plastic deformation during the HPT processing. A high dislocation density and volume fraction of grain boundaries enhance the long range diffusion of solute elements. Moreover, dislocations and grain boundaries act as nucleation centers for precipitates. As a consequence, the precipitation effects are facilitated in the UFG alloys compared to the conventional coarse-grained samples. This phenomenon was examined in this work by comparison of the precipitation sequence in Mg alloys with UFG structure and solution treated coarse-grained alloys.

• Periodical: Defect and Diffusion Forum (Volumes 273-276)
• Pages: 75-80
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.273-276.75
• Online since: February 2008
• Authors: Jakub Čížek, Ivan Procházka, Bohumil Smola, Ivana Stulíková, Vladivoj Očenášek, Rinat K. Islamgaliev, Olya B. Kulyasova
• Keywords: High Pressure Torsion (HPT), Mg Hardenable Alloys, Positron Annihilation Spectroscopy, Precipitation Effects, Severe Plastic Deformation (SPD), Ultrafine Grained Material

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