Formation mechanisms and mechanical properties of interfacial intermetallic compounds

界面金属间化合物的形成机制及力学性能

基本信息

批准号：
05452287
负责人：
YAMAGUCHI Masaharu
金额：
$ 4.61万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

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.

在Ti-Al二元系中，形成三种不同的金属间化合物，即Ti_3Al、TiAl和Al3Ti。这三种金属间化合物具有作为新型轻质高温材料的潜力，因此它们的机械性能已得到深入研究。特别是由TiAl和少量Ti_3Al组成的两相材料引起了人们的广泛关注。当铸造接近等原子成分的Ti-Al合金时，合金呈现出由TiAl和Ti_3Al片层组成的层状结构，Ti_3Al片层通常很薄并且夹在两个相邻的TiAl片层之间。因此，TiAl/Ti_3Al层状结构可以作为研究界面化合物对界面力学性能影响的有用载体。 Ti_3Al相的强度远高于TiAl相，TiAl和Ti_3Al之间较大的强度差异导致TiAl/Ti_3Al界面处存在较大的应变积累和不相容性。因此，当沿垂直于界面的方向受力时，TiAl/Ti_3Al/TiAl夹层结构是脆性的。在TiAl/Ti_3Al两相合金中添加各种元素，研究它们在两个组成相之间的分配行为，以寻找减小TiAl和Ti_3Al之间强度差异的元素。人们发现锡对界面表现出如此有益的作用。然而含Sn TiAl/Ti_3Al合金的力学测试结果并不如预期。这是因为含 Sn 的 Ti_3Al 相的细度比二元 Ti_3Al 相低，但仍然很脆。还研究了 MoSi_2 和 SiC 之间的界面，发现两相以不同于二元相的取向关系匹配。之前报道过。