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Engkir Sukirman
Center for Technology of Nuclear Industry Materials (PTBIN)-BATAN Kawasan Puspiptek Serpong 15314, Tanggerang
Materials Science & Nanotechnology

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THE STRUCTURAL AND MICROSTRUCTURAL characteristics IN THE MILLED Fe50C50 MAGNETIC COMPOSITES Setyo Purwanto; Engkir Sukirman
Jurnal Sains Materi Indonesia EDISI KHUSUS: OKTOBER 2007
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (760.437 KB) | DOI: 10.17146/jusami.2007.0.0.5113

Abstract

THE STRUCTURAL AND MICROSTRUCTURAL characteristics IN THE MILLED Fe50C50 MAGNETIC COMPOSITES. The structural and microstructural characteristics in the milled Fe50C50 magnetic composites have been investigated by the x-ray diffraction technique using Rietveld analysis method. The starting materials of composite were the pure iron (Fe) and carbon (C) powders (weight ratio Fe:C = 50:50). The composites were prepared by mixing Fe and C powders by high energy milling (HEM) at various milling time start from 1.5 to 4.5 h. The x-rays diffraction measurements were performed by using a Philips X-Ray Diffractometer, PW170 type at room temperature with CuKα radiation, 2θ range = 10°-100°, preset time = 1 sec, and step size = 0.020°. With a mechanical milling of 4.5 hours, the elemental powders undergo a better crystallization. It means that the amorphization. Of its components do not happen yet. The carbon elements in composites get a homogeneous strain field, while the iron elements get an inhomogeneous strain field. The crystallite size of C particles almost do not change yet until the milling time of 4.5 hours. This is presumably due to the C particles are trapped at the weld interfaces between the Fe particles. While, the Fe particles fracture into smaller segments on the milling time of 1.5 hours. On the further milling, the Fe particles undergo welding processes to be bigger crystallites. Magnetic parameter such as Hc, Ms and Ku were confirmed this suggestion.
THE INFLUENCE OF LATTICE STRAIN TO THE CRITICAL CURRENT DENSITY OF YBCO Engkir Sukirman; Didin S. Winatapura; Wisnu Ari Adi; Yustinus Purwatamanggalapratala
Jurnal Sains Materi Indonesia EDISI KHUSUS: OKTOBER 2007
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (388.252 KB) | DOI: 10.17146/jusami.2007.0.0.5105

Abstract

THE INFLUENCE OF LATTICE STRAIN TO THE CRITICAL CURRENT DENSITY OF YBCO. The influence of lattice strain to the critical current density of YBCO have been investigated. In this investigation it were prepared the YBCO superconductor samples which made by using a modified melt-textured growth (MMTG) method. The aim of doing this research is to investigate the relation between the critical current density and the lattice strain in YBCO superconductor. The structural and microstructural properties of the samples were characterized by the x-ray diffraction technique. The diffraction data were analyzed by means of a RIETAN software. While, the electrical properties of each samples were characterized by four point probe method. The lattice strains were then determined using the formula : <e2 hkl> = (U - Uo)/32 ln 2, where U is the refined FWHM parameters of the broadened peak due to the presence of an inhomogeneous strain field and U0 is the one due to the instrumental resolution only. The result of analysis indicate that the critical current densities and the lattice strains in YBCO samples have inversed correlation, i.e.when the lattice strain decreases, critical current increases, and conversely. The melt-process through 12 minutes may have possibly eliminated the weak links. Therefore, the critical current density increases, and the lattice strain decreases.
Co-Authors Didin S. Winatapura Setyo Purwanto Wisnu Ari Adi Yustinus Purwatamanggalapratala