personal

Me with Eminent Personalities

with Prof. NJ Kim (of POSTECH) and Dr. BS You (of KIMS)

with Prof. Hasse Fredricksson

with Prof. John Peripezko

with Prof. M.M.Makhlof

with Prof. John Hunt and other coleagues at BCAST

with Prof. Arne Dahle at PRICM6, Jeju, Korea

with Prof. Mark Easton, Prof. In-Ho Jung and others at LMT2013, UK

with Prof. Chris Grovernor, University of Oxford, UK

with my teachers and classmates of IIT-Kharagpur (@Chennai in 2014)

My China Visit (2008)

Inventions

Simultaneous Grain refinement and Modification of hypo-eutectic Al-Si alloys (INDIAN Patent No: 222043)

A new Al-Ti-C-Sr inoculant master alloy (Fig.1 &2) developed, results in simultaneous grain refinement and modification of A356 alloy. The Fig.3 below reveals the macrostructure of the A356 alloy before inoculation (designated as 0) and after inoculation (5, 30, 60, 120 min. holding time after melt inoculation). SEM photo micro-graphs shown in Fig.3 below demonstrate the extent of modification of eutectic silicon in un-inoculated and inoculated A356 alloy. Here the grain refinement is obtained due to the presence of TiC particles in the inoculant alloy, which act as substrates for heterogeneous nucleation of -Al. While the Al4Sr plate-lets in the inoculant alloy dissolve in molten A356 alloy at 720oC, and provide Sr for modification of eutectic silicon. Finally, both the primaries as well as the eutectic phases are refined by inoculating the A356 alloy melt with the new master alloy alone.

[Ref: A.K. Prasada Rao, K. Das, B.S. Murty and M. Chakraborty, “Al-Ti-C-Sr master alloy - A melt inoculant for simultaneous grain refinement and modification of hypoeutectic Al-Si alloys”, Journal of Alloys and Compounds, Vol. 480(2) (2009), pp. L49-51]

Fig.3

[Ref: A.K. Prasada Rao, K. Das, B.S. Murty and M. Chakraborty,“ Microstructural and wear behavior of hypoeutectic Al–Si alloy (LM25) grain refined and modified with Al–Ti–C–Sr master alloy ”WEAR, Vol.261 (2006) 2, pp. 133-139]

FIRST Manufacture of Al-Clad Magnesium alloy sheets during Twin-roll casting [Ref: http://www.scientific.net/MSF.618-619.467 ]

Cladding of Mg alloy with Al has been conducted by simultaneous casting, cladding and rolling a using twin-roll casting process. The as-cast microstructure shows the presence of Mg17Al12 in the reaction zone with good interfacial bonding between the Al and the base Mg alloy. Annealing of the clad sheet results in the additional formation of Mg2Al3 along the Mg/Al interface. Subsequent rolling of the as-annealed sheet reduces the thickness of the reaction zone with a resultant improvement in the formability of the clad sheet. Following figure illustrates the details.

[Ref: J. H. Bae,A.K. Prasada Rao, K.H. Kim and Nack J. Kim, "Cladding of Mg alloy with Al by Twin-Roll Casting", Scripta Materialia, Vol.64(9), (May 2011), pp.836-839

FIRST Successful Melt-conditioned Direct-Chill casting of Al and Mg alloys on PILOT-Plant scale

[ref: http://www.lime.ac.uk/documents/EPSRC_Centre-LiME_Annual-Report-2012.pdf ]

With the DC Caster I developed at BCAST

Fig.1 Macro-graphs of the transverse section of Diameter 80 mm DC cast billets of AA6060 alloy showing the general grain structures. The casting direction is from left to right. (a) Conventional DC casting, (b) MC-DC casting without adding grain-refiner

Fig.2 Micro-structure along the center of the DC cast AA6060 alloy billet (a) Conventional DC casting and (b) MC-DC casting without grain refiner addition [These microstructures correspond to the billet mentioned in Fig.1 above]

AA7032 alloy C-DC & MC-DC (left to right respectively)

As cast microstructure of AA7032 alloy billet, C-DC and MC-DC, respectively from left to right

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