Microstructure and mechanical properties of mechanically alloyed TiAl based alloys
- Pohang Univ. of Science and Technology (Korea, Republic of)
- Samsung Aerospace Industries, Changwon (Korea, Republic of)
Ti{sub 52}Al{sub 48} and (Ti{sub 52}Al{sub 48}){sup 100{minus}x}B{sub x} (x = 2,5) alloys have been produced by mechanical alloying in an attritor mill using prealloyed powders. Microstructure of binary Ti{sub 52}Al{sub 48} powders consists of grains of hexagonal phase whose structure is very close to Ti{sub 2}Al. (Ti{sub 52}Al{sub 48}){sub 95}B{sub 5} powders contains TiB{sub 2} in addition to matrix grains of hexagonal phase. The grain sizes in the as-milled powders of both alloys are nanocrystalline. The mechanically alloyed powders were consolidated by vacuum hot pressing (VHP) at 1,000 C for 2 hours, resulting in a material which is fully dense. Microstructure of consolidated binary alloy consists of {gamma}-TiAl phase with dispersions of Ti{sub 2}AlN and Al{sub 2}O{sub 3} phases located along the grain boundaries. Binary alloy shows a significant coarsening in grain and dispersoid sizes. On the other hand, microstructure of B containing alloy consists of {gamma}-TiAl grains with fine dispersions of TiB{sub 2} within the grains and shows the minimal coarsening during annealing. The vacuum hot pressed billets were subjected to various heat treatments, and the mechanical properties were measured by compression testing at room temperature. Mechanically alloyed materials show much better combinations of strength and fracture strain compared with the ingot-cast TiAl, indicating the effectiveness of mechanical alloying in improving the mechanical properties.
- OSTI ID:
- 225156
- Report Number(s):
- CONF-950201--; ISBN 0-87339-304-X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINIUM ALLOYS
BORON ALLOYS
CHEMICAL COMPOSITION
COMPRESSION STRENGTH
ELECTRON DIFFRACTION
EXPERIMENTAL DATA
GRAIN BOUNDARIES
GRAIN SIZE
HARDNESS
HEAT TREATMENTS
HOT PRESSING
INTERMETALLIC COMPOUNDS
MECHANICAL PROPERTIES
MICROSTRUCTURE
MILLING
NITRIDES
OXIDES
POWDERS
PRECIPITATION
TITANIUM ALLOYS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION