Microstructural Characterization and Mechanical Properties of Rapidly Solidified Al-Si Systems by Chill Block Melt-Spinning Technique.

AlـSi alloys with compositions (0, 0.1, 0.5, 0.9 and 1.3 wt.% Si) were manufactured by chill block melt spinning method. The resulting ribbons samples have been characterized by xـray diffraction (XRD) and scanning electron microscope (SEM). Detailed analysis of (XRD) shows that presence of f.c.c Al solid solution and Si particles embedded within the aluminum grains. Microstructural examination resulted that microstructure of the melt spun ribbons are more fine and uniformly distributed. Rapid solidification technology led to increase the solubility of Si in αـAl as confirmed by XRD. Micro hardness measurements were also carried out by Vickers microـhardness tester at applied load 25gm forced and different dwell time. It is concluded that the Vickers hardness values are sensitive to applied load and indentation time. It is also found that the highest values of Hv is sensitive to presence of Si as columnar shape with fine grained of Al by high cooling rate.

The Influence of Si Content on the Microstructure of Rapidly Solidified AlMnSi Foil

The AlMn and AlMnSi foils were fabricated by rapid solidification technology. The microstructures of the foils with various Si content were studied by transmission electron microscope (TEM). The phases of the foils were indentified by X-ray diffractometer (XRD); the phase transformation temperatures of the foils measured by differential scanning calorimeter (DSC). The results showed that addition of Si in the AlMn foil can improve the heat stability (phase transformation temperature) from 543K to over 873K. The addition of Si can change the phase structure of the foils. The phases of AlMn foil conclude Al and Al6Mn while the phases of AlMnSi foils with 3% Si or 5% Si addition become Al and Al4.01MnSi0.74. The addition of Si can also change the microstructure morphology of the foils from the rod, block and petal-like to the homogeneous globular. With the increase in Si content, the grain sizes of the foils were refined.

Formation of bulk β–FeSi2by annealing rapidly solidified α–FeSi2ribbons

Solidification of FeSi2alloy by single-roller rapid solidification technology was studied, and monophase α–FeSi2ribbons were obtained. Phase evolution of the monophase and metastable α–FeSi2ribbons during subsequent annealing was studied within situelectric resistance measurements. The results show that the metastable α–FeSi2phase transforms into the β–FeSi2phase at about 620 °C and then transforms into the α–FeSi2phase again at a higher temperature when heated. A new relatively simple method to prepare bulk β–FeSi2alloy, that is, formation of bulk β–FeSi2alloy by annealing monophase α–FeSi2alloy, is presented.