Formation and decomposition Processes of Non-Equilibrium phase by Mechanical alloying

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Major Results obtained in the last three years are listed below :1. The formation range of an amorphous phase in Ni-Zr system has been determined. The overmilling beyond the completion of an amorphous phase is found to cause the decomposition of an amorphous phase due to the accumulation of impurities from balls and vial.2. The formation of an amorphous phase has been confirmed by X-ray diffraction, neutron diffraction, EXAFS, DSC and low-temperature specific heat measurements in the Cu-Ta system characterized by a positive heat of mixing.3. The amount of energy accumulated during ball milling has been determined in the intermetallic compounds Cu5Zn8, NiZr and Fe2B by measuring the total heat release in the DSC spectra.4. We found that the ambient temperature in the range -150-200ﾟC has substantially affected the formation rate of an amorphous phase in Ni-Zr and CU-TA alloy system during mechanical alloying.5. Amorphous-like powders were synthesized by mechanical alloying of a mixture of CuBa and CuY in 2 : 1 atomic ratio. The technique in synthesizing high-Tc superconductor YBCO has been established by heat-treating the amorphous-like metallic powders at elevated temperature in oxygen-flow atmosphere.6. The iron nitrides were synthesized by mechanically alloying pure iron powders in NH3-atmosphere.