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Nowadays, Squeeze casting is considered as a convenient process for developing quality piston components. In this paper, casting methods such as squeeze casting and die casting techniques are used for compare the tensile behavior of Al-Si piston in the view of casted and heat-treated aspects. K-Nearest Neighbour (KNN) algorithm is used for predicting the tensile fracture of the squeeze casted Al-Si alloy. The proposed method is implemented in the MATLAB platform, and the tensile fracture in casting is compared with the experimental and predicted value. The scanning electron microscope analyzes the microstructural property and fractures analysis of the material. The maximum ultimate tensile strength of the casted and heat-treated specimen is 184 MPa and 297 MPa. The results indicate the proposed approach is an efficient method than the implemented Artificial neural network for predicting the tensile fracture in Aluminium-Silicon alloy materials. [ABSTRACT FROM AUTHOR]

The solidification behaviour of Al-Si based alloys with controlled additions of Eu (up to 200 ppm) and P (up to 10 ppm) was investigated using thermal analysis in a conventional die casting condition. The results indicate that P may be removed or involved into the formation of EuP phase. Furthermore, the formation of EuP phase appears to have a beneficial effect on the nucleation of Si and thereby the refinement of eutectic grains. A simultaneous modification of the eutectic Si and refinement of the eutectic grains was achieved by a combined addition of Eu and P, which is believed to be of extremely importance to optimize the number, size and size distribution of casting defects. The observation and analysis of pores using computed tomography strongly supports this argument. The obtained results in the present investigation can, therefore, give some novel insights in controlling the solidification microstructure of Al-Si based alloys. [ABSTRACT FROM AUTHOR]

Newtonian and Fourier analysis techniques were used to calculate the solid fraction and latent heat during the solidification of Al-8Si alloy and the subsequent results were used to study the effect of Sr modification on thermal diffusivity of the solidifying melt. The results indicate that the thermal diffusivity increased significantly with increase in Sr content. The increase in the thermal diffusivity was attributed to the increase in the electronic conduction of the modified alloy due to the decreased activity of the bifilm. The results also indicate that the latent heat evolved during solidification increased with increase in Sr concentration and was associated with the increase in the solidification range that occurred during the modification process. [ABSTRACT FROM AUTHOR]

The effect of individual and combined minor element additions (Sr, Sb, Mn, Cr and Al-5Ti-1B grain refiner) on microstructure and mechanical performance of a secondary cast aluminium piston alloy, with 1 wt-% Fe was investigated. It was observed that addition of Cr of up to 1% was better than a 0.53%Mn addition in improving tensile strength, impact energy and percent elongation of the alloy. The high mechanical performance recorded with addition of 1%Cr alloy was attributed to the significant reduction in porosity levels compared to all other minor element additions. It also resulted in a microstructure with fine compact intermetallic compounds. Other element additions also resulted in improved mechanical properties with 0.53%Mn performing better than 0.3%Mn + 0.2%Cr. Marginal improvements in mechanical performance were recorded with addition of 0.02%Sr (or 0.05%) and 0.02%Sb individually or in combination with 0.53%Mn. This was attributed to general increase in porosity and volume fraction of intermetallics. [ABSTRACT FROM AUTHOR]

The addition of CrB2and Sr into Al-10Si-0.3 Mg (wt.%)-based alloys not only modify the eutectic Si, but also refine the eutectic grains. CrB2particles were found to nucleate the eutectic grains, despite the AlP particles being partly removed or depleted by the interaction between Sr and AlP. Furthermore, P level was found to be one of the dominant factors that affect the nucleation of eutectic grains. CrB2addition with a low P level results in a refined eutectic grain size, despite less AlP particles being present to nucleate the eutectic grains. Porosity was found to be mainly located at the boundaries of eutectic grains, highlighting the importance of the refinement of eutectic grains to reduce the size and optimise the distribution of porosity. This investigation demonstrates a novel approach to refine eutectic grains and modify eutectic Si simultaneously into Al-10Si-0.3 Mg (wt.%)-based alloys, and thereby suggests possible industrial applications. [ABSTRACT FROM AUTHOR]

Electromagnetic continuous casting (EMCC) exhibits great potential for silicon purification by Al–Si method. Distribution of Al in Al–Si alloys with different aluminium contents during EMCC was investigated. The macrostructure of the Al–Si alloy ingots reveals that the content of primary silicon plates in hypereutectic alloys decreases from the bottom to the top of the ingots, and no obvious primary silicon plate exists in eutectic alloy. The fitting results of aluminium distribution in the alloys reveal two types of aluminium distribution patterns in hypereutectic Al–Si alloys: Scheil model for high temperature solidification and initial transient model for low temperature one. An apparent segregation coefficient of Al is proposed to characterise the solidification process, which is ∼0.83 in the hypereutectic alloys. [ABSTRACT FROM PUBLISHER]

Porosity formation in a Sr modified A356 alloy was investigated using microfocus X-ray imaging and directional solidification technology. In situ experimental results indicate that Sr addition enhances the effectiveness of oxide inclusions in the liquid aluminium alloy as pore nucleation sites and thus leads to a remarkable rise in the nucleation temperature. As pores are nucleated in high temperature region and far away from the solidification front, they can grow at a high growth rate for a relatively long time, and thus, significant increases in the volume fraction of porosity and particularly the number density of large pores are seen in the Sr modified alloy. The growth rate of pores decreases with the reduction in local liquid temperature, and it fluctuates violently during directional solidification. Addition of Sr weakens this fluctuation and decreases the average growth rate of pores. Addition of Sr has a considerable influence on the size distribution of pores. [ABSTRACT FROM AUTHOR]

A series of Al-5 wt-%Si alloys with or without 200 ppm Y addition have been produced using conventional casting and melt spinning respectively. The effects of Y addition and cooling rates on the refinement of eutectic Si have been investigated using thermal analysis, differential scanning calorimetry and multiscale microstructure characterisation techniques. In the case of conventional casting, the addition of up to 200 ppm Y was found to cause no modification effect. The eutectic Si presented a plate-like structure rather than a fibrous morphology. No significant Si twinning was observed. In the case of melt spinning, a higher cooling rate caused a much finer eutectic Si and Si twinning. The addition of 200 ppm Y promoted heavier multiply Si twinning. After a continuous cooling from 873 to 673 K, an Al2SiY phase was observed beside or within the Si particle. The refinement mechanism was also discussed. [ABSTRACT FROM AUTHOR]