Browsing by Author "MANDAL A."

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    Individual and synergistic effect of gamma alumina (?-Al2O3) and strontium on microstructure and mechanical properties of Al-20Si alloy
    (2019) ACHARYA M.; MANDAL A.
    An optimized combination of gamma alumina (4 wt.%) and strontium (0.1 wt.%) was incorporated in cast Al-20Si alloy to obtain fine form of silicon. During casting process, the amount of ?-Al2O3 was varied from 0.5�6 wt.% to refine primary Si and Sr was varied from 0.05�0.1 wt.% to modify eutectic Si. The results showed that the average size of primary Si is 24 ?m for addition of 4 wt.% ?-Al2O3 to the alloy whereas 0.1 wt.% Sr resulted in sphericity of eutectic Si to �0.6 and average length of �1.2 ?m. The thermal analysis revealed that ?-Al2O3 can act as potential heterogeneous nucleation sites. Moreover, simultaneous addition of ?-Al2O3 and Sr does not poison ?-Al2O3 particles and inhibit their nucleation efficiency as in the case of combined addition of phosphorous and strontium to Al-20Si alloy. Therefore, it was concluded that enhanced tensile strength, i.e., ultimate tensile strength (increase by 20%) and elongation (increase by 23%) in Al-20Si-4?-Al2O3-0.1wt.%Sr alloy as compared to as-cast Al-20Si alloy can be attributed to refinement of primary Si, modification of eutectic Si and the presence of ?(Al) in the alloy as evident from eutectic shift. � 2019 The Nonferrous Metals Society of China