Solidification, microstructure and mechanical properties of mg-nd-gd-zn-zr cast magnesium alloy with yttrium, erbium and samarium additions

• Main Author: M Elaswad, Ashraf Mahmood
• Format: Thesis
• Language: English; English; English
• Published: 2019
• Subjects: TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.uthm.edu.my/4/1/24p%20ASHRAF%20MAHMOOD%20M%20ELASWAD.pdf; http://eprints.uthm.edu.my/4/2/ASHRAF%20MAHMOOD%20M%20ELASWAD%20COPYRIGHT%20DECLARATION.pdf; http://eprints.uthm.edu.my/4/3/ASHRAF%20MAHMOOD%20M%20ELASWAD%20WATERMARK.pdf; http://eprints.uthm.edu.my/4/

The thesis project an investigation the effect of alloying elements Yttrium, Erbium and Samarium addition on the solidification characteristics, microstructure and mechanical properties of as-cast Mg-Nd-Gd-Zn-Zr magnesium alloy. The future automotive and aerospace industries will experience tremendous progress if magnesium alloys become an integral part of their production unit mainly because of their light weight. The main limitation to progress in this direction is paucity in the mechanical properties of magnesium alloys. Rare earth elements have been used as alloying elements to improve mechanical properties and introduce a new Mg-RE-Zn-Zr alloy with modified structure and strength. In addition, this study demonstrates the addition of RE to specific quantities that could be considered as major alloying elements that could lead to RE application extension limits. 0.1, 0.25, 0.5, 1, 1.5, 2 and 2.5 wt.% of Y, Er and Sm were added separately to Mg-Nd-Gd-Zn-Zr magnesium alloy. Thermal analysis was examined using CA-CCA. OM, SEM/EDS and XRD were used to investigate the microstructure of alloys, and the mechanical properties investigated include tensile and hardness tests. The results revealed that as Y level reached 0.25 wt.%, the solidification time was reduced to 27.28 s, the grain size decreased by 42.5%. Addition of 0.5 wt. % of Er caused a decrease in the solidification time of about 7.5 % which led to a decrease grain size of about 46 %. Furthermore, solidification time was reduced to 33.56 s which led to grain size reduction by 41.7 % as addition of 1.5 wt.% Sm. UTS and YS were improved by 37.3 % and 19.6 % respectively through addition of 0.25 wt. % of Y. Moreover, UTS increased by 21.4 % and 7.5 % for YS at 0.5 wt.% of Er. Addition of 1.5 wt. % of Sm led to increase UTS and YS by 14.5% and 15.9% respectively. In addition, the hardness value of base alloy was also recovered. The additives had a significant influence on the setting time, led to the improvement of the microstructure and mechanical properties, so that the magnesium alloy Mg-Nd-Gd-Zn-Zr was developed.