검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 4

        2.
        2004.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We report the crystallization and magnetic properties of non-equilibrium alloy powders produced by rod-milling as well as by new chemical leaching. X-ray diffractometry, transmission electron microscopy, differential scanning calorimetry and vibrating sample magnetometry were used to characterize the as-milled and leached specimens. After 400 h or 500 h milling, only the broad peaks of nano bcc crystalline phases were detected in the XRD patterns. The crystallite size, the peak and the crystallization temperatures increased with increasing Fe. After being annealed at for 1 h for as-milled alloy powders, the peaks of bcc are observed. After being annealed at for 1 h for leached specimens, these non-equi-librium phases transformed into fcc Cu and phases for the x=0.25 specimen, and into bcc phases for both the x=0.50 and the x=0.75 specimens. The saturation magnetization decreased with increasing milling time for alloy powders. On cooling the leached specimens from ,\;the magnetization first sharply increase at about for x=0.25, x=0.50, and x=0.75 specimens, repectively.
        4,000원
        3.
        2003.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We report on the formation and chemical leaching of non-equilibrium alloy produced by rod milling. X-ray diffractometry, transmission electron microscopy, differential scanning calorimetry, scanning electron microscopy, and vibrating sample magnetometry were used to characterize the as-milled and leached specimens. After 400 h, only the peak of the body-centered cubic type was present in the XRD pattern. The entire rod milling process could be divided into three different stages of milling: agglomeration, disintegration, and homogenization. The saturation magnetization, decreased with increased milling time, the of the powders before milling was about 113.8 emu/g, the after milling for 400 h was about 11.55 emu/g. Leaching of the Al in KOH of the Al at room temperature from the as-milled powders did not induce any significant change in the diffraction pattern. After the leached specimen had been annealed at for 1 hour, the nanoscale crystalline phases were transformed into the bcc Fe, cubic Co, and phases. On cooling the specimen from 85, the degree of magnetization increased slightly, then increased sharply at approximately 364.8, indicating that the bcc phase had been transformed to the Fe and Co phases.
        4,000원
        4.
        2002.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We report the structure, thermal and magnetic properties of a non-equilibrium alloy powder produced by rod milling and chemical leaching. An X-ray diffractometry(XRD), a transmission electron microscope(TEM), a differential scanning calorimeter(DSC), a vibrating sample magnetometer(VSM), and superconducting quantum interference device(SQUID) were utilized to characterize the as-milled and leaching specimens. The crystallite size reached a value of about 8.82 nm. In the DSC experiment, the peak temperatures and crystallization temperatures decreased with increasing milling time. The activation energy of crystallization is 200.5 kJ/mole for as-milled alloy powder. The intensities of the XRD peaks of as-milled powders associated with the bcc type structure formative at sharply increase with increasing annealing temperature. Above , peaks alloted to and are observed. After annealing at for 1h, the leached Ll specimen transformed into bcc -Fe and fcc Cu phases, accompanied by a change in the structural and magnetic properties. The saturation magnetization decreased with increasing milling time, and a value of about 8.42 emu/g was reached at 500 h of milling. The coercivity reached a maximum value of about 142.7 Oe after 500 h of milling. The magnetization of leached specimens as function of fields were higher at 5 K, and increased more sharply at 5 K than at 100 K.
        4,000원