Study on the Forming-Ability of Metastable Phases in Vapor Quenched Alloys Using High Temperatrue X-ray Diffraction

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In this project, we studied temperature-dependence of the structure and physical properties of nonequilibrium alloys produced by sputtering (vapor quenching process from high energy states) and obtained the following results.1) Using the high temperature sample stage, which was introduced by the present grant and installed on the X-ray diffraction equipment, we could observe X-ray diffraction patterns temperatures between 350 - 850 ^ﾟC.2) We observed X-ray diffraction patterns, magnetization, electrical resistivity, differential scanning calorimetry and Mossbauer spectra for amorphous Fe-Cu-Ag alloys produced by DC facing target type sputtering. The amorphous alloys crystallize above 400 K and transform to a metastable fcc phase with the same concentrations. They separate into pure bcc Fe and the pure fcc Cu and Ag above 670 K.3) We observed X-ray diffraction patterns, magnetization and electrical resistivity for nonequilibrium Fe-W alloys. The nonequilibrium Fe-rich bcc phase separate … More s into a more Fe-rich alpha phase and an intermetallic compound, the lambda phase, above 770 K. The amorphous phase displays high thermal stability and the crystallized temperature is about 1170 K. Above 1170 K. it transforms to the lambda phase and the bcc phase, but dose not transform to the mu phase which is the high temperature equilibrium phase.4) We observed X-ray diffraction patterns, magnetization and magnetostriction of nonequilibrium Fe-Pd alloys. The nonequilibrium Fe-rich bcc phase is maintained as a metastable phase below 470 K, but it separates into a more Fe-rich bcc phase and a Pd-rich fcc phase at 470 - 570 K. Above 570 K, moreover, the phase separation is enhanced and the disordered fcc phase becomes the L1_0 type ordered phase.These experimental results indicate that the metastable phase formation in the transient process from nonequilibrium phases to equilibrium phases by annealing breaks through the classical metallurgy based upon the equilibrium thermodynamics. We intend to do measurements of EXAFS and neutron diffractions. Less