Browsing by Author "Jha S."

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    Microstructural Changes in Hypoeutectic Al�Si Alloys by Low Shear and Vibration Induced Melt Conditioning Setup
    (2018) Jha S.; Aditya G.S.L.; Mandal A.; Dhindaw B.K.
    In the present work, refinement of microstructure in hypoeutectic Al�Si alloys, i.e., A356 and Al�7wt%Si has been reported. One of the mechanical technique, melt conditioning, was used to refine the microstructure. The technique involved subjecting the melt to low shear force by passing it through a slope at a temperature above its liquidus temperature. In addition to the shear force, vibration was induced into the melt during its flow by a simple setup for melt conditioning. Shear force along with vibrations led to enhanced refinement in both the alloys, the most prominent being A356 alloy. It has been suggested that higher fraction of fragmented oxide particles/films into the molten A356 alloy during the flow before solidification in the mould could enhance the nucleation centres. It was concluded that the bi-oxides such as MgAlO4 acted as effective heterogeneous nucleants for ?-Al. � 2018, The Indian Institute of Metals - IIM.
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    Optimization of Casting Process Parameters for Synthesis of Al-Nb-B Master Alloy
    (2019) Jha S.; Mandal A.; Srirangam P.
    Al-Nb-B master alloys were synthesized using commercial pure aluminum, niobium, and KBF4 salts. Two different sources of Nb (pure Nb powder and Al-60%Nb powder) were used to prepare the master alloy. Casting process parameters such as reaction time and melt stir time interval were varied to enhance the formation of in situ intermetallic particles in the master alloys. The size, shape and distribution of intermetallic particles in these master alloys were studied using microscopy techniques. The results show that the Al-5Nb-1B master alloy prepared with Al-60%Nb powders has a uniform distribution of intermetallic particles as compared to the master alloy prepared with pure Nb powders. Increase in boron content from 1�wt.% to 2�wt.% in the master alloys resulted in a higher fraction of intermetallic particles. Among all the master alloys synthesized, Al-5Nb-2B was observed to have the highest number of well-distributed intermetallic particles which could act as potential grain refiners of aluminum alloys. � 2018, The Author(s).