Browsing by Author "Diaa, A. Ahmed"

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    Effect of Zn addition on the microstructure and mechanical properties of cast, rolled and extruded Mg-6Sn-xZn alloys
    (ELSEVIER SCIENCE SA, 2017) El Mahallawy, N; Diaa, A. Ahmed; Akdesir, M; Palkowski, Heinz
    Tin and zinc have great potential as alloying elements in magnesium alloys in which they have a wide range of solid solubility. In the present study, the microstructure and mechanical properties of Mg-6Sn-xZn (x=0, 2, and 4 wt%) were investigated and compared in cast/heat treated, rolled at 350 degrees C from 10 mm to 2 mm and extruded at 350 degrees C with a ratio 40:1. The alloy composition and the applied process affected the mechanical properties. The Young's modulus increased with increasing Zinc content up to 2% and reached a maximum value of 40 GPa for the Mg-6Sn-2Zn alloy. In the case of the cast/heat treated condition, the ultimate tensile strength (UTS) and elongation to rupture increased with the Zn content, reaching maximum values of 189.7 MPa and 7.15%, respectively, for the Mg-6Sn-4Zn alloy. The maximum strength of the alloys in the rolled conditions was achieved for Mg-6Sn-4Zn alloy with a value of 253 MPa with 12.32% elongation while in the extruded conditions the Mg-6Sn-4%Zn alloy exhibited a maximum combination of strength and elongation of 276.33 MPa and 23.1%, respectively. The results are discussed with respect to the microstructure evolution, grain size and precipitates in the alloys.
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    Microstructure and mechanical properties of Mg-6Sn and Mg-6Zn alloys prepared by different processing techniques: a comparative study
    (WILEY-V C H VERLAG GMBH,, 2016) El Mahallawy, N.; Diaa, A. Ahmed; Akdesir, M.; Palkowski, H.
    The microstructure and mechanical properties of Mg-6Sn and Mg-6Zn are investigated and compared in cast/heat treated, rolled and extruded conditions. Compared to the heat treated alloys, the grain size of both alloys decreases while the volume fraction of precipitates increases by rolling and extrusion in Mg-6Sn alloy at 350 degrees C due to dynamic recrystallization and dynamic precipitation of intermetallic phases. Zinc has a stronger grain refining effect than tin in the heat treated alloys while the opposite effect is found in the rolled and extruded alloys. For the heat treated alloys the Mg-6Sn the strength reached 158.7 MPa with elongation 5.2% while Mg-6Zn exhibited a higher strength of 183.7 MPa and 8.4% elongation. In rolled condition the strength of Mg-6Sn reached 224 MPa with 1.6% elongation while Mg-6Zn exhibited a lower strength of 124 MPa and a lower ductility of 0.5% elongation due to susceptibility to hot shortness. Extrusion of Mg-6Sn alloy resulted in the maximum attained strength of 281 MPa and an elongation of 6.1% while Mg-6Zn cracked during extrusion due to hot shortness. The results obtained are discussed with respect to microstructure evolution in both alloys.