Materials Literature
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It is known that a metastable crystalline thin-film structure can often be stabilized by choosing a suitable substrate. For single-crystal thin films, this pseudomorphic growth has been attributed to the stabilization of the metastable phase by epitaxial growth. However, in the polycrystalline structure, the mechanism…
Temperature dependence of the intrinsic coercivity (HcI ) of Pr17 (Fe0.9 Co0.1 )83−x Bx has been measured above room temperature and analyzed by expressing HcI as the difference between a term proportional to the anisotropy field (HA ) and a term corresponding to a local demagnetization field. The fraction in HA avail…
A combination of hydrogen decrepitation (HD) and jet milling (JM) has been used to produce powder for the processing of permanent magnets. The procedure has proved to be very successful for both NdFeB (Neomax) alloys and the NdDyFeNbB high coercivity alloys. The magnets produced by the HD/JM process showed excellent c…
Specific heat C of κ-(BEDT-TTF) 2 Cu(NCS) 2 was measured between T c (10.4 K) and 3 K. An anomaly around T c was observed. The specific heat data show unusual bending below T c in the C / T versus T 2 plot. At the lowest temperatures, C obeyed the T 3 law and no residual T -linear contribution was observed.
We report loss separation measurements performed on 1.8% SiFe nonoriented 0.2-mm laminations of variable grain size 20 μm≤s≤130 μm, in the frequency range 1 Hz≤ f≤300 Hz and peak induction range 0.7 T≤B≤1.5 T. It is shown that the excess loss behavior is well reproduced by the equation Pe =k(Bf)3/2, in agreement with…
Theoretical backscattering amplitude and phase functions, B(k) and \ensuremath{\varphi}(k), used in extended x-ray-absorption fine structure (EXAFS) studies show strong features in their k dependence which can be identified as a ``generalized Ramsauer-Townsend effect.'' This effect is studied in detail for elements wi…
We have studied the consequence of structure on the magnetic properties of 304 stainless steel in two distinct crystalline states. Ordinary 304 stainless steel has an fcc structure and is nonmagnetic at room temperature. By using a vapor quenching method, we have fabricated single-phase metastable bcc 304 stainless st…
Neutron diffraction experiments on Y(Ti,Fe)12 have been carried out to investigate the crystallographic structure and magnetic properties of these compounds. In the ThMn12-type structure, with a space group of I4/mmm, Fe and Ti atoms are distributed on three nonequivalent crystallographic sites. A preferential site oc…
After reviewing the main aspects of Barkhausen effect (BE) phenomenology and the principal theoretical models proposed for its interpretation, a new experimental and theoretical approach is presented. It is shown that definite progress in the comprehension of BE phenomenology is achieved by restricting BE experiments…
Starting from elemental powders, hard-magnetic Nd-Fe-B can be produced by mechanical alloying and a solid-state reaction. Due to the short reaction time at relatively low temperatures (typically 30 min at 700 °C), the magnetically isotropic particles are microcrystalline and show a high coercivity. These powders can b…
A model is proposed for interstitial diffusion in a disordered alloy. Diffusion is described in terms of single-jump processes with an activation energy and a prefactor depending on the chemical and physical structure of the initial and final sites. Site-dependent activation energies, prefactors, selective blocking fa…
A novel magnetostriction measurement tool is developed for a thin soft-magnetic film on a nonmagnetostrictive substrate. The sensitivity is at least an order of magnitude better than prior art, and is adequate to measure a magnetostriction coefficient as small as 10−7–10−8 for a film as thin as 30 nm on a glass wafer…
A novel icosahedral alloy, ${\mathrm{Al}}_{65}$${\mathrm{Cu}}_{20}$${\mathrm{Fe}}_{15}$, produced in both a thermodynamically metastable and stable phase, has been studied with $^{57}\mathrm{Fe}$ M\"ossbauer spectroscopy, x-ray diffraction, and differential thermal analysis. It was found that the M\"ossbauer spectrum…
Intermetallic compounds of the type RE(TM1−xMx)12 with RE=Y, Er; TM=Fe, Co; M=Si, Ti, V of the ThMn12 tetragonal crystal structure have been studied by the singular point detection technique and high-resolution neutron powder diffraction in order to (a) evaluate both the rare-earth and transition-metal sublattice cont…
Results are reported from angle-integrated, angle-resolved, and resonant photoemission measurements on cleaved MnO single crystals using synchrotron radiation. Normal-emission spectra from a cleaved (100) surface indicate that the relative dispersion of Mn 3d states in the valence band is less than \ifmmode\pm\else\te…
The primary structure of the ribonuclease inhibitor from pig liver has been determined by amino acid sequence analysis. The N alpha-acetylated polypeptide chain of 456 amino acids consists of 15 homologous leucine-rich repeats, characterized by leucyl residues at constant positions. Two types of alternating repeats oc…
Enhanced magnetically isotropic properties are observed in melt-spun flakes of the Nd2Fe14B(Si) type. The magnetic enhancement, referred to as HIREM, includes a remanent magnetization equal to 8–9.3 kG (with saturation magnetization measured between 15.2 and 15.7 kG), and an energy product up to 19 MGOe. Both of these…
A recently developed density-functional method for calculating elastic moduli of crystals is generalized to include phason elasticity in incommensurate crystals. The theory is applied to hypothetical icoshedral quasicrystals based on interactions embodied in the pair correlation functions of a dense-random-packing mod…
Effects of the spin reorientation in Nd2Fe14B below Ts =135 K on the hard magnetic properties of melt-spun Nd-Fe-B ribbons are reported. As the ribbons are cooled from room temperature, the shape of the second quadrant demagnetization curve is maintained down to 150 K, with an intrinsic coercivity Hci which increases…
Extensive x-ray diffraction (XRD) and magnetic measurements were done on Nd15 Fe77 B8 magnet alloy green compacts after cold isostatic pressing following a pulsed 2-T field (CIP) and die-pressing under a static 1.2-T perpendicular field (DP1) or parallel field (DP2), and on those after sintering. An alignment factor F…