Relationship between microstructure and performance of Al-Ti-C master alloy at different cooling rates Grain refining process used in aluminum alloys has a significant role for preventing columnar, coarse grains and encouraging fine grain formation. Fine-grained alloys have high strength, good toughness, fatigue resistance and high resistance to hot tearing. In addition, fine grains improve the surface quality and reduce the need for machining. That is the main reason for produce alloys with fine grain microstructure. There are different methods for reducing grain size, including: the dynamic, thermal and chemical methods. In the most effective and widely used method a chemical is added to molten alloy. In the past decades, Al-Ti and Al-Ti-B grain refiners were used for aluminum alloys, but in recent years, because of weaknesses of these grain refiners, a new grain refiner in the form of Al-Ti-C master alloys was introduced. In the other hand, Although Al–Ti–B master alloys are widely used as aluminum grain refiners, but there are problems in their application. Because of great properties of Al–Ti–C refiners, they can be considered as a suitable candidate for use instead of Al–Ti–B master alloys. In recent years, Al–Ti–C refiners have attracted a huge attention among researchers. In this study, by addition of titanium and carbon powders with the specified weight ratio to molten aluminum, Al-3Ti-1C master alloy produced at 900 and 1200 °C. Because, the microstructure and phases formed during the solidification are dependent on the cooling rate, so, master alloys, produced at 900 ?C and 1200 ?C, cooled at four different rates 1, 1.9, 4 and 7 ° C/s. By spectrometric analysis technique, the recovery percent of the elements in the master alloy is determined. To identify the phases formed in grain refiner, the X -ray diffraction analysis (XRD) was used. The results clarified that the phases Al 3 Ti, TiC and Ti 6 C 3.75 are formed in master alloy. Master alloy that produced at different cooling rates was added to the molten aluminum at 720 °C and fading time was studied. The results show that grain refiner that solidified at 4 °C/s is more effective than other cooling rates. On the other hand, by reducing the cooling rate, fading time of master alloy increased. . .
