An alternative approach in ceramic shell investment casting of AZ91D magnesium alloy: In situ melting technique

2014 ◽  
Vol 214 (4) ◽  
pp. 988-997 ◽  
Author(s):  
Hassan Jafari ◽  
Mohd Hasbullah Idris ◽  
Ali Ourdjini
Keyword(s):  
Magnesium Alloy ◽  
Investment Casting ◽  
Ceramic Shell ◽  
Az91d Magnesium Alloy ◽  
Alternative Approach ◽  
Melting Technique

Effect of Thickness and Permeability of Ceramic Shell Mould on In Situ Melted AZ91D Investment Casting

2013 ◽  
Vol 465-466 ◽  
pp. 1087-1092
Author(s):  
Hassan Jafari ◽  
Mohd Hasbullah Idris ◽  
Ali Ourdjini
Keyword(s):  
Surface Quality ◽  
Investment Casting ◽  
Solidification Rate ◽  
Ceramic Shell ◽  
Good Surface ◽  
Melting Technique ◽  
Shell Mould ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes

The influence of ceramic shell mould thickness and permeability on investment casting of AZ91D alloy using in-situ melting technique was investigated. AZ91D granules together with melting flux were charged into two different moulds having different thicknesses and four various permeabilities; then were heated at 650°C in order to be melted. Visual inspection and scanning electron microscopes were used to characterise the surface quality of cast samples. Thermal analysis was employed to further analyse the effect of mould thickness on cooling and solidification behaviour of molten metal. The findings of this research showed that thinner mould provided higher solidification rate, which is believed to favour in-situ melting enhancement. It enabled melting of the granules at the investigated temperature resulted in suppressing mould-metal reaction and producing cast samples with good surface quality. The results also showed that the permeability of shell mould was ineffective in suppressing mould-metal reaction.

Grain Refinement of AZ91D Magnesium Alloy by In Situ Al4C3 Particles

2011 ◽  
Vol 306-307 ◽  
pp. 429-432
Author(s):  
Hui Han ◽  
Hua Ming Miao ◽  
Sheng Fa Liu ◽  
Yang Chen
Keyword(s):  
Magnesium Alloy ◽  
Grain Refinement ◽  
Synthesis Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Az91d Magnesium Alloy ◽  
Average Grain Size ◽  
Central Regions ◽  
Heterogeneous Nucleus

Experiments were conducted to fabricate the Al4C3 particles by powder in-situ synthesis process under argon atmosphere and examine the grain refinement of AZ91D magnesium alloy with the addition of 0.6%Al4C3(hereafter in mass fraction,%). By means of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS), the results show the successful fabrication of Al4C3 particles. After adding 0.6%Al4C3, the average grain size of AZ91D magnesium alloy decreased from 360μm to 243μm. Based on the differential thermal analysis (DTA) results and calculations of the planar disregistry between Al4C3 and α-Mg, Al4C3 particles located in the central regions of magnesium grains can act as the heterogeneous nucleus of primary α-Mg phase.

Al-TiC in situ composite coating fabricated by low power pulsed laser cladding on AZ91D magnesium alloy

2018 ◽  
Vol 435 ◽  
pp. 1187-1198 ◽  
Author(s):  
Liuqing Yang ◽  
Zhiyong Li ◽  
Yingqiao Zhang ◽  
Shouzheng Wei ◽  
Fuqiang Liu
Keyword(s):  
Magnesium Alloy ◽  
Low Power ◽  
Composite Coating ◽  
Laser Cladding ◽  
Pulsed Laser ◽  
In Situ Composite ◽  
Az91d Magnesium Alloy

Oxidation and Melting Characterizations of AZ91D Granules during In Situ Melting

2011 ◽  
Vol 311-313 ◽  
pp. 631-634 ◽  
Author(s):  
Hassan Jafari ◽  
Mohd Hasbullah Idris ◽  
Ali Ourdjini ◽  
Saeed Farahany
Keyword(s):  
Electrical Resistance ◽  
Heating Process ◽  
Resistance Furnace ◽  
X Ray ◽  
Characteristic Temperatures ◽  
Az91d Magnesium Alloy ◽  
Melting Technique ◽  
Different Temperatures ◽  
Electrical Resistance Furnace

In this research, the oxidation and melting behaviour of AZ91D magnesium alloy granules was investigated throughout using in-situ melting technique when the granules were covered by flux. The granules were heated inside an electrical resistance furnace at four different temperatures of 650, 700, 750 and 800 °C for 30 min. Thermal analysis was used to detect the granules characteristic temperatures during the technique. The products of the heating process were examined visually and characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. The results showed that due to occurrence of severe oxidation and combustion, particularly at 800 °C, a significant amount of the granules transformed to a powdered state. The presence of the mould materials within the oxidation residue was detected indicating that severe mould-magnesium reaction occurred during heating. It was found that the granules melted during the heating process. However, the presence of oxides on the granules prevented them from fusing to form a single melt.

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