An Analytical Electron Microscopy Characterization of Melt-Spun Iron/Rare-Earth/Boron Magnetic Materials

1985 ◽  
Vol 58 ◽  
Author(s):  
R.C. Dickenson ◽  
K.R. Lawless ◽  
G.C. Hadjiipanayis
Keyword(s):  
Electron Microscopy ◽  
Magnetic Properties ◽  
Rare Earth ◽  
Melt Spinning ◽  
Analytical Electron Microscopy ◽  
High Energy ◽  
Ion Milling ◽  
Analytical Electron ◽  
Strategic Element ◽  
Microscopy Characterization

Iron/rare-earth/boron permanent magnet materials have recently been delveloped to reduce the need for the strategic element cobalt, which was previously the primary canponent of high-energy magnets. These materials are generally produced by annealing rapidly solidified ribbons or by conventional powder metallurgy techniques. This paper will report results from an analytical electron microscopy characterization undertaken to establish the relationship between the magnetic properties and the microstructure of two iron/rare-earth/boron (Fe/RE/B) alloys. Ribbons of Fe75Pr15B10 and Fe77Tb15B8 were produced by melt-spinning. To obtain optimum magnetic properties, both alloys were then annealed at 700°C, the FePrB ribbons for 6 minutes and the FeTbB ribbons for 90 minutes. Foils for transmission electron microscopy were prepared by ion-milling the ribbons on a cold stage and examined using a Philips 400T TEM/STEM equipped with an energy dispersive x-ray unit.

Preparation of Backthinned Ceramic Specimens

1985 ◽  
Vol 43 ◽  
pp. 182-183
Author(s):  
A. T. Fisher ◽  
P. Angelini
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Vacuum System ◽  
Back Surface ◽  
Surface Microstructure ◽  
Ion Milling ◽  
Near Surface ◽  
Depth Profiles ◽  
Analytical Electron ◽  
Ion Implanted

Analytical electron microscopy (AEM) of the near surface microstructure of ion implanted ceramics can provide much information about these materials. Backthinning of specimens results in relatively large thin areas for analysis of precipitates, voids, dislocations, depth profiles of implanted species and other features. One of the most critical stages in the backthinning process is the ion milling procedure. Material sputtered during ion milling can redeposit on the back surface thereby contaminating the specimen with impurities such as Fe, Cr, Ni, Mo, Si, etc. These impurities may originate from the specimen, specimen platform and clamping plates, vacuum system, and other components. The contamination may take the form of discrete particles or continuous films [Fig. 1] and compromises many of the compositional and microstructural analyses. A method is being developed to protect the implanted surface by coating it with NaCl prior to backthinning. Impurities which deposit on the continuous NaCl film during ion milling are removed by immersing the specimen in water and floating the contaminants from the specimen as the salt dissolves.

AEM of a Ag-Y-Ba-Cu superconductor precursor material

1993 ◽  
Vol 51 ◽  
pp. 1192-1193
Author(s):  
A. J. Strutt ◽  
M. T. Simnad ◽  
E. Lavernia ◽  
K. S. Vecchio
Keyword(s):  
Melt Spinning ◽  
Analytical Electron Microscopy ◽  
Oxide Phase ◽  
Metallic State ◽  
Ion Milling ◽  
X Ray ◽  
Cu Alloy ◽  
Precursor Material ◽  
Analytical Electron ◽  
Spinning Process

Analytical electron microscopy (AEM) has been used to characterize a Ag-rich superconductor precursor material whose composition (before oxidation) was based on 10 wt.% of a YBa2Cu3 alloy and 90 wt.% Ag, and the same material after an oxidation heat treatment of 690°C for 24 hours. The material had been produced by a melt spinning process as a metallic alloy to permit deformation of the material (in the metallic state) prior to subsequent oxidation to form the ceramic superconducting Y-Ba-Cu oxide phase.The microstructure was characterized using a Philips CM30 AEM, at 300 kV, using specimens thinned to electron transparency by ion-milling. Energy dispersive X-ray spectroscopy (EDX) was performed using the same instrument, with a Link Analytical solid-state X-ray detector with an ultra-thin window.In the as-formed condition, the Y-Ba-Cu alloy phase exists as discrete particles at the triple points of the relatively fine (approx. 250 nm.)

Phase Identification in TiB2-Ni Composites by Analytical Electron Microscopy

1981 ◽  
Vol 39 ◽  
pp. 138-139
Author(s):  
P. S. Sklad ◽  
J. Bentley ◽  
A. T. Fisher ◽  
G. L. Lehman
Keyword(s):  
Electron Microscopy ◽  
Cutting Tools ◽  
Analytical Electron Microscopy ◽  
High Hardness ◽  
Phase Identification ◽  
Second Phase ◽  
Binder Phase ◽  
Ion Milling ◽  
X Ray ◽  
Analytical Electron

The transition metal diboride TiB2 is characterized by high hardness and high melting point (3253 K) . These properties make this material attractive for applications such as valve components in coal liquefaction plants and cutting tools. Liquid phase hot pressing using nickel as the fluidizing medium allows densification at lower temperatures than when using TiB2 powders alone, but the nickel and TiB2 react to form a complex multiphase microstructure. The purpose of this investigation was to identify the nickel-rich binder phase. The material examined was taken from a cylindrical compact hot pressed at ∼1720 K. During pressing most of the original 15 mol % Ni exuded from the initial mixtures. Specimens 3 mm dia were prepared for analytical electron microscopy (AEM) examination by mechanical lapping followed by ion milling.A typical microstructure of the TiB2-Ni composite examined at 120 kv by conventional transmission electron microscopy (TEM) is shown in Fig. 1. The microstructure is characterized by TiB2 grains bonded by a second phase which was observed at multiple grain intersections. X-ray energy dispersive spectroscopy (EDS) measurements were made using a Philips EM400T/FEG. probe sizes of ∼10 nm dia and probe currents of ∼5 nA were used so that measurements could be made in thin regions of the binder phase, where beam broadening was small. Typical x-ray spectra from an intergranular region and an adjacent TiB2 grain are shown in Fig. 2. The results of standardless quantitative analyses of binder phase spectra indicated a composition (for Z > 11) of at least 95% Ni.

Rare Earth Oxide Dispersoid Stability and Microstructural Effects in Rapidly Solidified Ti3Al and Ti3A1-Nb

1985 ◽  
Vol 58 ◽  
Author(s):  
J. A. Sutliff ◽  
R. G. Rowe
Keyword(s):  
Rare Earth ◽  
Titanium Aluminide ◽  
Melt Spinning ◽  
Analytical Electron Microscopy ◽  
Rare Earth Oxide ◽  
Microstructural Effects ◽  
Analytical Electron ◽  
The Matrix ◽  
Rapidly Solidified ◽  
Titanium Aluminide Alloys

ABSTRACTThe microstructures of titanium aluminide alloys containing a rare earth oxide dispersion have been characterized using analytical electron microscopy. The alloys, based on Ti3A1 (alpha-2), contained 0 to 10.7 atom% Nb and 0.5 atom% Er. Alloys were rapidly solidified by melt spinning and were subsequently consolidated by HIP and extrusion. The microstructure of each alloy was examined in the as-cast, as-HIP'ed, and as-extruded conditions. A fine dispersoid spaced less than 100 nm apart was observed in ribbon aged at 750°C. The effects of processing conditions on the dispersoid distribution as a function of matrix chemistry were studied. Hot deformation was also examined to investigate the nature of the interaction between the dispersoids and the matrix during deformation.

scholarly journals Analytical Electron Microscopy Characterization of a Temperature-Stable Relaxor Ferroelectric Ceramic

2019 ◽  
Vol 25 (S2) ◽  
pp. 2118-2119
Author(s):  
Teresa Roncal-Herrero ◽  
John Harrington ◽  
Aurang Zeb ◽  
Steven J Milne ◽  
Andy P. Brown
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Ferroelectric Ceramic ◽  
Relaxor Ferroelectric ◽  
Analytical Electron ◽  
Microscopy Characterization

Microanalytical investigation of sintered FE-Nd-B magnets

1986 ◽  
Vol 44 ◽  
pp. 824-825
Author(s):  
R. Ramesh ◽  
T. A. Bielicki ◽  
G. Thomas
Keyword(s):  
Electron Microscopy ◽  
Magnetic Properties ◽  
Analytical Electron Microscopy ◽  
Alloy System ◽  
Magnetic Alloy ◽  
Microstructural Investigation ◽  
Analytical Electron ◽  
Hard Magnetic Alloy

Fe-Nd-B is emerging as an important hard magnetic alloy system. The magnetic properties, in particular, the coercivity, are strongly influenced by the microstruetura1 condition of the magnet and are subject to degradation by various factors which can be understood only with the use of analytical electron microscopy. This investigation focuses on the characterization of inclusions discovered within a magnet which exhibits a kinked B-H loop.(Fig.1). Based on the microstructural investigation, an appraisal is made of the effect of these particles on the magnetic properties.

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