Precession Electron Diffraction Detection and Phase Mapping of Retained Austenite and Carbides in a Heat Treated Low Alloy Carbon Steel Using a JEOL ARM 200 TEM with an AppFive Topspin System for Synchronized Beam Scanning and Precession
Retained austenite in heat treated steels is usually measured using X-Ray diffraction, with protocols outlined in ASTM Standard E975 [1]. Retained austenite has been measured in high alloy steels with large grains of retained austenite using EBSD [2]. However, low alloy steels heat treated to reduce retained austenite may have small grains of retained austenite that cannot reliably be detected by EBSD [3] or X-Ray diffraction.
Characteristics of Retained Austenite in Quenched High C-High Cr Alloy Steels
In this paper, the morphologies of martensite and retained austenite for 1.5 mass%C-12 mass%Cr and 1 mass%C-8 mass%Cr steels were observed by means of optical microscopy, XRD, SEM/EBSD and TEM. The amount of retained austenites was quantitatively investigated and compared with XRD, EBSD and TEM observation methods. The retained austenites were distributed in the form of a block type and a film type in the martensite structures. For the 1.5 mass%C-12 mass%Cr steel, the amount of block type retained austenite and film type one are almost equal in three distinct regions of carbide; primary carbide, secondary carbide and without carbide. In the case of 1 mass%C-8 mass%Cr steel, as to film type retained austenite there are not so much differences among those regions. However, block type retained austenites are distributed with much amount, especially in the region around primary carbide. [doi:10.2320/matertrans.MRA2008161]
Microstructure of the solder-casting zone in bridges of dental gold alloys.
The composition and structure were studied in the cast and in the solder of bridges which had failed clinically. Both materials were gold alloys but with different contents of Pt, Ag and Zn. The metallographic investigation revealed defects mostly in the solder, situated in the subsurface layer. SEM studied of the fracture surface revealed large porosites and a structure of dense parallel lines--striations--, indicating that the material had failed from fatigue. The materials in the fractured bridges were identified by micro-probe measurements. It was stated that cast material and solder material used together, were of different composition.