1994 Fiscal Year Final Research Report Summary
Formation mechanisms and mechanical properties of interfacial intermetallic compounds
| Project/Area Number |
05452287
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Structural/Functional materials
|
|---|
| Research Institution | KYOTO UNIVERSITY |
|---|
Principal Investigator |
YAMAGUCHI Masaharu Dept.of Materials Science and Engineering, Kyoto University, 工学部, 教授 (90029108)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
INUI Haruyuki Dept.of Materials Science and Engineering, Kyoto University, 工学部, 助手 (30213135)
|
|---|
| Project Period (FY) |
1993 – 1994
|
| Keywords | Interfacial intermetallics / Mesoscopic / Interfacial structure / High resolution electron microscopy / Mechanical properties |
|---|
| Research Abstract |
In the Ti-Al binary system, three different intermetallic compounds, namely Ti_3Al, TiAl and Al3Ti are formed. These three intermetallic compounds have potential as new light-weight high-temperature materials and thus their mechanical properties have been intensively investigated. In particular two-phase materials composed of TiAl and a small volume fraction of Ti_3Al have been attracting considerable attention. When Ti-Al alloys with nearly equiatomic compositions are cast, the alloys exhibit the lamellar structure composed of TiAl and Ti_3Al lamellae, The lamellae of Ti_3Al is often thin and sandwiched between the two neighboring TiAl lamellae. The TiAl/Ti_3Al lamellar structure can thus be used as a useful vehicle for studying effects of interfacial compound on the mechanical properties of interface. The Ti_3Al phase is much stronger than the TiAl phase and the large difference in strength between TiAl and Ti_3Al results in the large strain accumulations and incompatibilities at the TiAl/Ti_3Al interface. Thus, the TiAl/Ti_3Al/TiAl sandwich structure is brittle when it is stressed along the direction perpendicular to the interface. Various elements were added to TiAl/Ti_3Al two-phase alloys and their partition behavior between the two constituent phases was investigated to find elements which reduce the difference in strength between TiAl and Ti_3Al. Tin is found to exhibit such an beneficial effect on the interface. However, the results of the mechanical testing of Sn-bearing TiAl/Ti_3Al alloys were not as good as expected. This is because the Sn-bearing Ti_3Al phase exhibits a lower stringth than the binary Ti_3Al phase but it is still brittle.
Interface between MoSi_2 and SiC was also investigated and the two phases were found to be matched in an orientation relationship which was different from that reported previously.
|
