2001 Volume 48 Issue 1 Pages 69-76
The combustion synthesis of dense TiAl intermetallic compound with Co/Al sintering additive was investigated.The raw Ti/Al (Ti:Al=1:1) powder mixed with Co/Al (Co:Al=1:1) was prepared from elemental Ti, Al, and Co powders. The compacts made from the powders were reacted by the thermal explosion combustion synthesis. After this, density, phases, microstructure, and mechanical properties (Vickers hardness, compressive strength of the obtained product) were measured.
The nearly full dense product could be obtained by moderate addition of the Co/Al additive. The product was consisted of TiAI, Ti3Al, and solidified Ti-Al-Co melt phases with about 20-25 mm grain size. The Vickers hardness of the product was about Hv=330, and the fracture strength was σf=1350MPa (εf=0.25).
In a previous experiment, the nearly full dense compound could be synthesized by addition of Ni/Al powder. The present product is softer than the previous compound with the Ni/Al powder addtion, and showed a slight plastic deformation. Therefore, the sintering additive affected the strength of the TiAl compound. However, the product was still too brittle to use for structure materials, and it is necessary to improve the brittleness.
