Effect of B on the microstructure and mechanical properties of mechanically milled TiAl alloys

Journal Article · Tue Sep 01 04:00:00 EDT 1998 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-998-0105-2· OSTI ID:655344

Kim, S H; Kim, N J ^[1]; Chung, H H ^[2]; Pyo, S G ^[3]; Hwang, S J ^[4]

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1. Pohang Univ. of Science and Technology (Korea, Republic of)
2. Korea Gas Corp., Kyunggi (Korea, Republic of)
3. Hyundai Electronics Industries Co., Ltd., Kyunggi (Korea, Republic of)
4. Daejin Univ., Kyunggi (Korea, Republic of). Dept. of Materials Engineering

The present study is concerned with {gamma}-(Ti{sub 52}Al{sub 48}){sub 100{minus}x}B{sub x} (x = 0, 0.5, 2, 5) alloys produced by mechanical milling vacuum hot pressing (VHPing) using melt-extracted powders. Microstructure of the as vacuum hot pressed (VHPed) alloys exhibits a duplex equiaxed microstructure of {alpha}{sub 2} and {gamma} with a mean grain size of 200 nm. Besides {alpha}{sub 2} and {gamma} phases, binary and 0.5 pct B alloys contain Ti{sub 2}AlN and Al{sub 2}O{sub 3} phases located along the grain boundaries and show appreciable coarsening in grain and dispersoid sizes during annealing treatment at 1300 C for 5 hours. On the other hand, 2 pct B and 5 pct B alloys contain fine boride particles within the {gamma} grains and show minimal coarsening during annealing. Room-temperature compressing tests of the as-VHPed alloys show low ductility, but very high yield strength >2100 MPa. After annealing treatment, mechanically milled alloys show much higher yield strength than conventional powder metallurgy and ingot metallurgy processed alloys, with equivalent ductility to ingot metallurgy processed alloys. The 5 pct B alloy with the smallest grain size shows higher yield strength than binary alloy up to the test temperature of 700 C. At 850 C, 5 pct B alloy shows much lower strength than the binary alloy, indicating that the deformation of fine 5 pct B alloy is dominated by the grain boundary sliding mechanism.

• Sponsoring Organization: USDOE
• OSTI ID: 655344
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 9 Vol. 29; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
ANNEALING
BORON ALLOYS
INTERMETALLIC COMPOUNDS
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
MICROSTRUCTURE
TEMPERATURE RANGE 0400-1000 K
TITANIUM ALLOYS