Friction stir processing of the AZ91 magnesium alloy with SiC particles

Purpose: Purpose The main purpose of the research was friction modification by means of material stirring (FSP – Friction Stir Processing) of the surface layer of the AZ91 magnesium alloy with SiC particles. Design/methodology/approach: For the introduction of SiC particles and the formation of the composite structure in the surface layer of the magnesium alloy, the original multi chamber technology (MChS), developed as part of this study, was used. The scope of research verifying the effectiveness of the friction modification included both macro- and microscopic evaluation of the structural changes triggered by the treatment. Findings: The research results showed that friction modification of the AZ91 magnesium alloy leads to a strongly refined structure and intensively dispersed SiC ceramic particles in the surface layer of the magnesium alloy, resulting in the formation of the composite structure of the metal-ceramic type. In the stirred zone (SZ), a prevalence of equiaxed grains sized 2–15μm was observed, whereas the degree of refinement of structure depended on the treatment parameters, especially on the rotation speed of the stir tool. In the thermomechanically affected zone (TMAZ), deformed grains dominated, the location of which corresponded to the direction of the displacement of the plastified material during the FSP treatment. SiC particles have been found both in the SZ and in the TMAZ. Practical implications: The obtained results prove that using the FSP technology to modify the surface layer of magnesium alloys with SiC particles is an effective and promising solution with a high application potential, which allows for forming the material structure to a great extent. Originality/value: The structural research has shown that the Multi Chamber System technology enables a controlled and virtually lossless introduction of an additional phase in the course of the single-stage treatment, and minimizes the dislocation of the powder beyond the working area of the working tool.

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Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę (zadania 2017)