Microstructure and mechanical properties of mechanically alloyed TiAl based alloys

Book · Sun Dec 31 00:00:00 EST 1995

OSTI ID:225156

Chung, H H; Kim, N J ^[1]; Hwang, S J ^[2]

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1. Pohang Univ. of Science and Technology (Korea, Republic of)
2. 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; TRN: IM9621%%86
• Resource Relation: Conference: Annual meeting and exhibition of the Minerals, Metals and Materials Society (TMS), Las Vegas, NV (United States), 12-16 Feb 1995; Other Information: PBD: 1995; Related Information: Is Part Of Gamma titanium aluminides; Kim, Y.W. [ed.] [UES, Inc., Dayton, OH (United States). Materials and Processes Div.]; Wagner, R. [ed.] [GKSS Research Center, Geesthacht (Germany). Inst. for Materials Research]; Yamaguchi, Masaharu [ed.] [Kyoto Univ. (Japan). Dept. of Materials Science and Engineering]; PB: 1023 p.
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
TITANIUM ALLOYS
MILLING
MICROSTRUCTURE
MECHANICAL PROPERTIES
ALUMINIUM ALLOYS
BORON ALLOYS
INTERMETALLIC COMPOUNDS
POWDERS
HOT PRESSING
GRAIN SIZE
GRAIN BOUNDARIES
PRECIPITATION
HEAT TREATMENTS
X-RAY DIFFRACTION
TRANSMISSION ELECTRON MICROSCOPY
CHEMICAL COMPOSITION
OXIDES
NITRIDES
ELECTRON DIFFRACTION
HARDNESS
COMPRESSION STRENGTH
EXPERIMENTAL DATA