Enhancement of TiB Grain Refining Effect on A356 Gravity Die Casting with the Addition of Yttrium
- 1 Departmentof Mechanical Engineering, Universiti Tunku Abdul Rahman, Kuala Lumpur, Malaysia
- 2 Departmentof Mechanical Engineering, Universiti Tunku Abdul Rahman, Kuala Lumpur, Malaysia
Abstract
The present work investigates the effect yttrium on the grain refining efficiency of Al-5Ti-1B in gravity die cast A356 aluminum alloy. A series of casting experiments were carried out in which the Ti and B contents were maintained constantly at 0.1 and 0.02 wt% respectively. The inoculation level of yttrium was manipulated at the amount of 0, 0.1, 0.2, 0.3, 0.4 and 0.5 wt%. Microstructural characterization of the as-cast A356 alloy was investigated by means of optical microscope and its phases are detected by XRD. XRF is used to determine the contents of inoculating elements such as Ti, B and Y so that their actual optimal ratio in the casting can be approximated. The mechanical properties tested are tensile strength and hardness. The inoculation of yttrium was found to enhance the grain refinement effect of Al-5Ti-1B grain refiner and improve the mechanical properties. The optimal weight percentage of yttrium was discovered to be 0.3. The grain refining efficiency of combining yttrium and Al-5Ti-1B on A356 aluminum alloy was mainly attributed to the heterogeneous nucleation of TiB 2 and TiAl 3 particles which were dispersed more evenly in the presence of yttrium and also as a result of α-Al grain growth restriction by AlY 3 compound precipitated at grain boundaries during solidification.
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