Papers by Author: B.S. Murty

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Authors: N. Das, U.D. Kulkarni, S.K. Pabi, B.S. Murty, G.K. Dey
Abstract: Recent studies indicate that the existing criteria for amorphous phase formation are not precise. This study emphasizes that the extent of deviation from the linear relationship of the chemical contribution to enthalpy of the solid solution with the enthalpy difference between the amorphous phase and the constituent elements is a measure of tendency to bypass amorphous phase formation. Mechanical alloying experiments on a number of compositions in Al-Ni-Ti system showed that the compositions, not following the aforesaid relation, yield partial or no amorphization.
Authors: T. Shanmugasundaram, V. Subramanya Sarma, B.S. Murty, Martin Heilmaier
Abstract: The microstructure and mechanical properties of nano-crystalline 2219 Al alloy (Al-6.4Cu-0.29Mn, all in wt %) was studied. Nanocrystalline powders were produced from gas atomized 2219 Al alloy powders by high energy ball milling at room temperature. Powders were collected at different milling times and X-ray diffraction (XRD) analysis was used to evaluate grain size. High Vickers hardness (250HV), high compressive strength (920 MPa) and low ductility (2%) were observed in unimodal bulk nanostructured 2219 Al alloys consolidated to 99% density by hot pressing (HP). In addition, these nanocrystalline powders were blended with 15, 30 and 50% of (gas atomized) coarse-grained powders to obtain balanced mechanical properties of enhanced yield and ultimate strength and reasonable ductility and toughness as compared to either conventional or nanocrystalline 2219 alloys.
Authors: J. Bhatt, B.S. Murty
Abstract: This paper attempts to optimize the bulk metallic glass forming compositions using enthalpy of chemical mixing (DHchem) as thermodynamic, mismatch entropy (DSs/kB) as topological and configurational entropy (DSconfig/R) as statistical parameters. The product of DHchem and DSs/kB which is termed as PHS in the DSconfig/R range of 0.9 to 1.0 can be correlated strongly to glass forming ability. PHS being an important parameter has been used to design the quaternary and quinary Bulk Metallic Glass compositions from ternary compositions. This has been demonstrated for two Zr rich quaternary systems in Zr-Ti-Cu-Ni and Zr-Cu-Ni-Al based bulk metallic glasses. By weighing approach of PHS of four Zr rich quaternary systems and one non-Zr rich systems a new Zr rich quinary bulk metallic glass in Zr-Ti-Cu-Ni-Al system is designed. Mechanical alloying is used to prepare the bulk amorphous powder at the compositions predicted by the model in order to validate the model.
Authors: K.R. Ravi, Indumathi, R. Subramanian, B.S. Murty
Abstract: In the present work, synthesis of bulk Fe amorphous alloy by mechanical alloying of 70Fe-15Cr-4Mo-5P-4B-1C-1Si powders followed by consolidation of powders using Spark Plasma Sintering process is reported. The evolution of phase, microstructure, relative density and hardness of amorphous alloy as a function of spark plasma sintering temperature is discussed. Transmission electron microscopy investigation has shown partial divitrification of amorphous matrix into nanocrystalline phase during spark plasma sintering of amorphous Fe alloy. The hardness of amorphous alloy sintered at 525 – 575°C are in the range of 675 - 725 MPa.
Authors: Jatin Bhatt, Sundaram Kumar, B.S. Murty
Abstract: Based on the thermodynamic and topological approach, Cu60Zr30Ti10 has been identified as the best bulk metallic glass forming composition in Cu-Zr-Ti system. Bulk metallic glass has been successfully produced using mechanical alloying of elemental blends and consolidation of the resulting glassy powders into pellets of 8 mm diameter. Dry sliding wear of glassy pellets at different annealed states showed that the relaxed metallic glass has excellent wear resistance.
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