Mechanical alloying to produce L1{sub 2} phases in the Al-Zr system
- Los Alamos National Lab., NM (United States). Center for Materials Science
- Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Metallurgical and Materials Engineering
The group IV trialuminides offer a combination of high melting points with low densities. In addition, high oxidation resistance and low susceptibility to hydrogen embrittlement make them potential candidates for elevated temperature structural applications. However, Al{sub 3}Ti shows no compressive ductility at temperatures below 600 C, preventing its use as a structural material. Fine and homogeneous microstructures obtained through novel processing techniques such as mechanical alloying (MA) may be the key to developing low-temperature toughness in these alloys. Achieving high-temperature strength may require adding continuous ceramic or metallic reinforcements. Issues relating to the synthesis of an L1{sup 2} structure during mechanical alloying are examined for the binary Al{sub 3}Zr composition. MA is capable of producing homogeneous, fine-grained alloys in the solid state, thus providing a processing technique that can avoid the large-grained inhomogeneous structures resulting from conventional casting processes. In addition, a fine uniform dispersion of oxides or carbides can be added to the microstructure. MA can also be used to produce metastable microstructures. For example, the MA of elemental aluminum and zirconium hydride powders at the Al-25 at.% Zr composition results in the formation of Al{sub 3}Zr having the metastable L1{sub 2} structure rather than the stable DO{sub 23} structure.
- OSTI ID:
- 186767
- Journal Information:
- Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 1 Vol. 34; ISSN 1359-6462; ISSN XZ503X
- Country of Publication:
- United States
- Language:
- English
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