Electron microscopy of rapidly solidified weldments in a powder-metallurgy Al-Fe-Ce alloy
Al-Fe-Ce alloys are rapid-solidification/powder metallurgy (RS/PM) products that offer significant advantages over conventional ingot metallurgy (IM) aluminum alloys for elevated-temperature applications. Through rapid solidification, the formation of coarse, primary intermetallics is suppressed and solidification instead occurs to a primary chi-aluminum structure. Subsequent powder consolidation and thermomechanical processing promote the formation of a high volume fraction (25 to 35%) of extremely fine thermally stable dispersoids in a matrix of submicrometer chigrains. This unique microstructure provides moderate to high room-temperature mechanical properties up to 300 C. Recent work has demonstrated that capacitor-discharge welding can successfully generate high-integrity joints in Al-Fe-Ce alloys. The extremely rapid heating and cooling rates associated with this process allow the generation of a rapidly solidified fusion zone without degradation to the surrounding base-metal microstructure. In addition, the simultaneous application of pressure during fusion-zone solidification suppresses the formation of hydrogen-induced porosity. In the original study, the investigation of weld-zone solidification characteristics was limited by the exclusive use of light microscopy for microstructure characterization. The purpose of the present work was to characterize capacitor-discharge weld-solidification phenomena in greater detail through the use of transmission electron microscopy.
- Research Organization:
- Ohio State Univ., Columbus, OH (USA). Dept. of Welding Engineering
- OSTI ID:
- 5125729
- Report Number(s):
- AD-A-213559/8/XAB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360101 -- Metals & Alloys-- Preparation & Fabrication
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
ALUMINIUM ALLOYS
CASTINGS
CERIUM ALLOYS
COOLING
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
HEATING
IRON ALLOYS
JOINTS
MECHANICAL PROPERTIES
MELTING
METALLURGY
MICROSCOPY
MICROSTRUCTURE
PHASE TRANSFORMATIONS
POWDER METALLURGY
PROCESSING
RARE EARTH ALLOYS
TRANSMISSION ELECTRON MICROSCOPY
WELDED JOINTS
ZONE MELTING