Microstructural characterization of a rapidly solidified ultrahigh strength Al{sub 94.5}Cr{sub 3}Co{sub 1.5}Ce{sub 1} alloy
The microstructure of a rapidly solidified Al{sub 94.5}Cr{sub 3}Co{sub 1.5}Ce{sup 1} alloy has been examined in detail by means of high resolution transmission electron microscopy (HRTEM) and atom probe field ion microscopy (APFIM). In the as-quenched microstructure, nanoscale particles of a solute-enriched amorphous phase and an Al-Cr compound are dispersed in randomly oriented fine grains of {alpha}-Al ({sub 200 nm}). The interface between the Al grains and the amorphous particles is not smooth but irregular with atomic protrusions and concavities, suggesting that interfacial instability occurs during the solidification process. Nanoscale amorphous particles are formed as a result of solute trapping within the rapidly grown Al grains. After annealing at 400 C for 15 minutes grain growth occurs, and the interface of the Al grains is smoothed. The amorphous region trapped within the grains if crystallized to an Al-Cr compound, but no icosahedral phase has been confirmed. The APFIM results have revealed that Cr and Ce atoms have a similar partitioning behavior, i.e., they are rejected from the {alpha}-Al phase and partitioned into the trapped amorphous regions. On the other hand, Co atoms are not partitioned between the two phases in the as-quenched state but are partitioned into the {alpha}-Al grains in the annealed alloys being rejected from the Al compounds and finally form Al-Co compounds. Based on these microstructural characterization results, the origins of high strength of this alloy are discussed.
- Research Organization:
- National Research Inst. for Metals, Tsukuba (JP)
- OSTI ID:
- 20023137
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 31, Issue 3; Other Information: PBD: Mar 2000; ISSN 1073-5623
- Country of Publication:
- United States
- Language:
- English
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