Investigation of the effect of rare earth additives on solidification of as-cast ZRE1 magnesium alloy

Saad Sheggaf, Zayad Mohamed (2017) Investigation of the effect of rare earth additives on solidification of as-cast ZRE1 magnesium alloy. PhD thesis, Universiti Tun Hussein Onn Malaysia.

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Abstract

The thesis project investigates the effect of alloying elements Pr, Y and Er addition on the solidification characteristics, microstructure and mechanical properties of as-cast ZRE1 magnesium alloy. Automotive and aerospace industries shall witness the advancement to the next generation if magnesium alloys becomes an integral part of their manufacturing unit primarily because of its light weight. The main limitation which hinders the progress in this direction is the inferior mechanical properties of Mg alloys. Rare earth elements were used as alloying elements for improving the mechanical properties and to introduce a new Mg-RE alloy with modified structure and strength. In addition, this study demonstrates the addition of RE at specific amounts which could be considered as main alloy elements that may lead to extent limitation of RE application. 0.25, 0.5, 0.75, 1, 1.25 and 1.75 wt.% of Pr, Y and Er were added separately to ZRE1 magnesium alloy. Thermal analysis was examined using CA-CCA. XRD, OM and FESEM/EDS were used to investigate the microstructure of alloys, and the mechanical properties investigated include tensile and hardness tests. The results revealed that as Pr level reached 1.25 wt.%, the solidification time was reduced to 52 s, the grain size decreased by 12%. Addition of 0.5 wt.% of Er caused a decrease in the solidification time of about 20% which led to a decrease grain size of about 16%. Furthermore, solidification time decreased of about 23 s which led to grain size reduction by 24% as addition of 1 wt.% Y. UTS and YS were improved by 10% and 11% respectively through addition of 1.25 wt.% of Pr. Moreover, UTS increased by 17% and 8% for YS at 1.25 wt.% of Y. Addition of 0.25 wt.% of Er led to increase UTS and YS by 15% and 7% respectively. In addition, the hardness value of base alloy was also recovered. The additives had a significant effect on the solidification time, leading to the refinement of microstructure, and improved the mechanical properties, thus the ZRE1 magnesium alloy was developed. Lastly, casting and machining parameters of the developed alloys are recommended to be examined.

Item Type:Thesis (PhD)
Subjects:T Technology > TA Engineering (General). Civil engineering (General) > TA401-492 Materials of engineering and construction. Mechanics of materials
ID Code:10007
Deposited By:Mr. Mohammad Shaifulrip Ithnin
Deposited On:28 May 2018 14:34
Last Modified:28 May 2018 14:34

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