Structural Phase Transformations in Alloys: An Electron Microscopy Study

Author(s):  
G. Tendeloo ◽  
D. Schryvers ◽  
L. E. Tanner ◽  
D. Broddin ◽  
C. Ricolleau ◽  
...  
2002 ◽  
Vol 17 (6) ◽  
pp. 1287-1297 ◽  
Author(s):  
Zhengkui Xu ◽  
James L. Shull ◽  
Waltraud M. Kriven

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.


1990 ◽  
Vol 04 (06) ◽  
pp. 399-407
Author(s):  
J. Q. LI ◽  
Z. X. ZHAO ◽  
F. H. LI ◽  
D. Y. YANG ◽  
G. S. SHI

A transmission electron microscopy study has confirmed some new features of thermal variations of the microstructure in the high-T c superconducting compound YBa 2 Cu 3 O y. The changes of domain structures and the nucleation process of the tetragonal phase with the increase of temperature are demonstrated by series of images taken under in-situ heating observations. At temperature near 250°C, two new sets of planar defects have been observed along the directions of a and b-axes, respectively. It has been identified that a continuous structural phase transition, from orthorhombic to tetragonal phase, occurs at about 480 °C. The structural properties of the tetragonal phase have been studied at 700°C.


Author(s):  
Julie A. Martini ◽  
Robert H. Doremus

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.


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