A Transmission Electron Microscopy study of the B2-DO3 ordering phase transformations in Fe-6.3wt% Si after rapid quenching and annealing

1988 ◽  
Vol 46 ◽  
pp. 772-773
Author(s):  
J. E. Wittig
Keyword(s):  
Phase Transformations ◽  
Melt Spinning ◽  
Magnetic Behavior ◽  
Microscopy Study ◽  
Rapid Quenching ◽  
Electron Microscopy Study ◽  
Silicon Alloys ◽  
Brittle Behavior ◽  
Transmission Electron ◽  
Rapidly Solidified

Iron-silicon alloys are extensively used in transformer cores owing to exceptional soft magnetic behavior that is optimized at about 6.5 wt% Si. Unfortunately this equilibrium microstructure is completely brittle at room temperature. The brittle behavior coincides with the onset of an ordering reaction of the disordered A2 into the B2 and DO3 superlattices at approximately 5 wt% Si. Rapid solidification methods have been shown to improve the ductility of Fe- 6.3 to 6.5 wt% Si. In this investigation, rapidly quenched and annealed samples of Fe-6.3wt% Si were examined in the transmission electron microscope (TEM) to study the ordering phase transformations of this alloy and its effect on the mechanical behavior.Samples of Fe-6.3wt% Si were rapidly solidified by melt spinning into ribbons (t=20-80 microns) as well as by splatting using an opposing piston double anvil method. Rapidly quenched samples were subsequently heat treated in evacuated quartz tubes at 500, 600, and 700 C for 24 h.

Hot-stage Transmission Electron Microscopy Study of Phase Transformations in Hexacelsian (BaAl2Si2O8)

2002 ◽  
Vol 17 (6) ◽  
pp. 1287-1297 ◽  
Author(s):  
Zhengkui Xu ◽  
James L. Shull ◽  
Waltraud M. Kriven
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Phase Transformations ◽  
Antiphase Domain ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Hexagonal Structure ◽  
Second Phase ◽  
Transmission Electron

Phase transformations in synthetic hexacelsian were investigated by hot-stage transmission electron microscopy. A second phase transformation from an orthorhombic to hexagonal structure was identified in the synthetic hexacelsian at approximately 700 °C. The hexacelsian was found to exhibit a sequence of phase transformations on heating of hexagonal (P63/mcm)–orthorhombic (Immm)–hexagonal (P6/mmm). Antiphase domain boundaries, which were observed in P63/mcm and Immm phases, were absent in the P6/mmm phase. Crystal symmetries of the three phases were determined by convergent beam electron diffraction, and space group symmetries were derived by comparison of experimental selected area electron diffraction patterns with computer-simulated patterns.

New Insight into the Banded Microstructure of Rapidly Solidified Ag-Cu Alloys : Experiment and Theory

1990 ◽  
Vol 205 ◽  
Author(s):  
E. Y. Yankov ◽  
S. M. Copley ◽  
J. A. Todd ◽  
M. I. Yankova
Keyword(s):  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Thin Plates ◽  
Continuous Growth ◽  
Growth Structure ◽  
Transmission Electron ◽  
Surface Laser ◽  
Far From Equilibrium ◽  
Coupled Growth ◽  
Rapidly Solidified

AbstractA transmission electron microscopy study has revealed that the banded microstructure produced in Cu-61.7 at. pct. Ag after surface laser melting and resolidification is not due to a cellular breakdown of the interface as previously thought, but consists of alternating regions of the extended metastable solid solution, y, and a coupled growth structure containing thin plates of y and the copper-rich phase β'. The spacing of this coupled growth structure is approximately 100 Å, which is less than half the minimum spacing yet observed for coupled growth from the melt in Ag-Cu.In order to explain the banded microstructure a theoretical model has been developed based on a finite elements solution of the diffusion equation in the melt, the interface response functions for continuous growth derived by Aziz and Kaplan and a recently developed theory for coupled growth that includes far-from-equilibrium regimes by Yankov et al..

Factors influencing adhesive bonding at the bone/implant interface

1992 ◽  
Vol 50 (2) ◽  
pp. 1114-1115
Author(s):  
Julie A. Martini ◽  
Robert H. Doremus
Keyword(s):  
Electron Microscopy ◽  
Adhesive Bonding ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Bone Implant ◽  
Factors Influencing ◽  
Lr White ◽  
Transmission Electron ◽  
New Zealand White Rabbits ◽  
Scanning Electron

Tracy and Doremus have demonstrated chemical bonding between bone and hydroxylapatite with transmission electron microscopy. Now researchers ponder how to improve upon this bond in turn improving the life expectancy and biocompatibility of implantable orthopedic devices.This report focuses on a study of the- chemical influences on the interfacial integrity and strength. Pure hydroxylapatite (HAP), magnesium doped HAP, strontium doped HAP, bioglass and medical grade titanium cylinders were implanted into the tibial cortices of New Zealand white rabbits. After 12 weeks, the implants were retrieved for a scanning electron microscopy study coupled with energy dispersive spectroscopy.Following sacrifice and careful retrieval, the samples were dehydrated through a graduated series starting with 50% ethanol and continuing through 60, 70, 80, 90, 95, and 100% ethanol over a period of two days. The samples were embedded in LR White. Again a graduated series was used with solutions of 50, 75 and 100% LR White diluted in ethanol.

Transmission Electron Microscopy study of Bi-based superconducting phases

1990 ◽  
Vol 48 (4) ◽  
pp. 50-51
Author(s):  
J.G. Wen ◽  
K.K. Fung
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystals ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Space Groups ◽  
Superconducting Phases ◽  
Ceramic Samples ◽  
Transmission Electron ◽  
Modulated Structures

Bi-based superconducting phases have been found to be members of a structural series represented by Bi2Sr2Can−1Cun−1On+4, n=1,2,3, and are referred to as 2201, 2212, 2223 phases. All these phases are incommensurate modulated structures. The super space groups are P2/b, NBbmb 2201, 2212 phases respectively. Pb-doped ceramic samples and single crystals and Y-doped single crystals have been studied by transmission electron microscopy.Modulated structures of all Bi-based superconducting phases are in b-c plane, therefore, it is the best way to determine modulated structure and c parameter in diffraction pattern. FIG. 1,2,3 show diffraction patterns of three kinds of modulations in Pb-doped ceramic samples. Energy dispersive X-ray analysis (EDAX) confirms the presence of Pb in the three modulated structures. Parameters c are 3 0.06, 38.29, 30.24Å, ie 2212, 2223, 2212 phases for FIG. 1,2,3 respectively. Their average space groups are all Bbmb.

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