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The effect of thermal processing parameters on the mechanical properties of aluminium alloy foam

Puspitasari D., Ginta T. L., Puspitasari P., Mustapha M.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 91, nr 1

12--17

EN

Purpose: The purpose of this study was to investigate the influence of three thermal processing parameter called stress relieving on mechanical properties of the aluminium alloy foam. Design/methodology/approach: The samples were undergone by stress relieving method using vacuum furnace. Hardness measurement was carried out using microhardness Vickers at 150 mN load and 15 s loading time. Compressive strength, plateau stress and energy absorption were calculated using a universal testing machine. Findings: It was found that the highest value of hardness of 192.78 Hv was obtained when the stress relieving process is set with the following parameters: heating (500°C); holding time (120 min) and stabilization temperature (450°C). Since higher heating temperature and longer holding time produce sample with larger grain size and has an adverse effect on the hardness value It was revealed that the mechanical properties of aluminium alloy foam were enhanced when the heating temperature was decreased, holding temperature was diminished and the stabilization temperature was increased. Overall, the presented results showed that the thermal processing parameters such as heating temperature, holding time and stabilization temperature have a significant influence on improving the mechanical properties of aluminium alloy foam. Research limitations/implications: The properties of closed-cell aluminium alloy foam are highly sensitive and depend on the post heat treatment process. The processing parameters should be controlled in order to manipulate the properties of closed-cell aluminium alloy foam. Originality/value: To investigate the influences of these processing parameters on the physical and mechanical properties of the closed-cell aluminium alloy foam.

2

Morphology of aluminium with nickel addition on sand casting process

Puspitasari P., Fauzan R., Ginta T. L., Mustapha M., Puspitasari D.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 87, nr 1

13--17

EN

Purpose: This research aimed to examine the morphology, elemental changes, and phase in the aluminium cast alloys with variations in nickel addition of 1%, 2% and 3%. Design/methodology/approach: Aluminium 98% was melted in sand casting process. The sand casting process was operated at 7000C and atmospheric pressure. The addition of nickel contain of 92.19% of its element. Specimens consist of 4 pieces Al-Ni with the size of 1 x 1 x 0.5 cm for morphological testing, while for phase identification testing consist of 4 pieces Al-Ni with the size of 1 x 1 x 2 cm. The morphological testing was performed using FEI Inspect S50 Scanning Electron Microscope (SEM) and the phase characterisation was conducted using Nikon ME5 Optical Microscope. Findings: The results showed that the addition of 1% nickel in the aluminium cast product could affect the morphology in granular shape with as similar size, at 2% nickel addition also has granular shape, while at 3% of nickel addition, the morphology of Al-Ni was in elongated shape. Phase identification of Al-Ni cast alloy shows that there were Al matrix with nickel that spread in grain boundary of Al. By increasing the percentage of nickel, it shows that the nickel dominated the grain boundary of Al. These results shows that Al-Ni alloy can be produced at simple route on sand casting process. Research limitations/implications: Sand casting process with 80% silica sand, 10% bentonite, 5% water. Raw material of aluminium contains of 92-99% of purity. Nickel as addition element contain of 90-92% purity. Practical implications: The addition of nickel should be prepared wisely in term of the calculation of alloying treatment because it will effect the mechanical properties of Al alloy itself. This research can be improved by varying the temperature of casting process, variation of nickel percentage, and observation of mechanical properties of Al-Ni alloy. Originality/value: Simple route of making Al-Ni alloy using sand casting method in laboratory and also the observation of nickel addition in aluminium matrix as the result of casting product.

3

Statistical optimization of stress relieving parameters on closed cell aluminium foam using central composite design

Puspitasari D., Ginta T. L., Mustapha M., Sallih A., Puspitasari P.

Archives of Materials Science and Engineering

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2018

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Vol. 89, nr 2

55--63

EN

Purpose: This study concerns about the influence of stress relieving parameters on the hardness of closed cell aluminium foam using central composite design. Design/methodology/approach: The responses of three stress relieving parameters: heating temperature, holding time and stabilization temperature are studied and analysed through 20 experimental runs designed according to central composite design. The results of microhardness test corresponded to the microstructural evaluation of closed-cell aluminium foam using optical microscope. Analysis of Variance (ANOVA) technique is employed to study the significance of each parameter on the microhardness property. In this process the design has five levels for each parameter. The stress relieving process of the samples were performed using a vacuum furnace. The hardness test was conducted using a micro hardness tester LM247AT and the microstructure of the samples were obtained using optical microscopy technique. Findings: It was found that the highest value of hardness of 192.78 HV was obtained when the stress relieving process is set with the following parameters: heating (500°C); holding time (120 min) and stabilization temperature (450°C). Since higher heating temperature and longer holding time produce sample with larger grain size and has an adverse effect on the hardness value. Research limitations/implications: Liquid metal and powder metallurgical processing still produces a non-uniform and poorly reproducible cellular structure. This cellular structure demonstrates poor quality difference on decomposition and melting temperature, called anisotropic early expansion. Originality/value: To improve the poor cellular structure quality, stress relieving method is proposed in this study. Stress relieving method can improve the microstructure of the material.