Synthesis of metastable aluminum-based intermetallics by mechanical alloying
We have used mechanical alloying (MA) to prepare fine-grained powders of Al 25 at. % X (X = Ti, Zr, Hf) having the metastable cubic L1{sub 2} structure. Hexane (C{sub 6}H{sub 14}) is added to the milling media to avoid the agglomeration of the aluminum powder. Carbon from the decomposition of the hexane incorporates into the powder to form a fine dispersion of carbides. These carbides are beneficial because they limit grain growth during consolidation and add strength to the alloy. We have consolidated the mechanically alloyed powders using conventional hot-pressing and non-conventional dynamic pressing. We used hot pressing to consolidate mechanically alloyed L1{sub 2}-Al{sub 3}Ti powder in the presence of excess of Al. The compact has the DO{sub 22} structure. Its room-temperature compressive strength is 1.2 GPa (exceeding that of cast Al{sub 3}Ti by a factor of 10). At 400{degrees}C, the compressive strength decreases to 1 GPa. The ductility, which is negligible at room temperature, increases to 6% at 400{degrees}C. We used dynamic pressing to consolidate L1{sub 2}-Al{sub 5}CuZr{sub 2} powder. The compact, having the L1{sub 2} structure, has fine grains (44 nm) and a fine dispersion of ZrC precipitates (7 nm). Its hardness is in the range of 1030 kg mm{sup {minus}2}. Current efforts are to investigate ternary alloys based on fine-grained trialuminides which include a ductile second phase. 26 refs., 8 figs.
- Research Organization:
- Los Alamos National Lab., NM (USA)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 5750686
- Report Number(s):
- LA-UR-91-1490; CONF-9105182--2; ON: DE91013651
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360101* -- Metals & Alloys-- Preparation & Fabrication
ALKANES
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM BASE ALLOYS
CARBIDES
CARBON COMPOUNDS
ELECTRON MICROSCOPY
FABRICATION
HAFNIUM ALLOYS
HEXANE
HOT PRESSING
HYDROCARBONS
INTERMETALLIC COMPOUNDS
MATERIALS WORKING
MICROSCOPY
ORGANIC COMPOUNDS
POWDERS
PRESSING
SYNTHESIS
TITANIUM ALLOYS
TRANSMISSION ELECTRON MICROSCOPY
ZIRCONIUM ALLOYS