Abstract
This paper reports on the effects of carbon, nitrogen, boron, and oxygen on the microstructure and properties of gamma-TiAl alloys. It has been found that nitrogen and boron are capable of altering the solidification structure, whereas the others are not. The additions of >1 at.% B or 0.5 at.% N changed the cast structure from columnar to equiaxed with fine grain sizes. As a result, the strength has been significantly increased. Additional results on phase and structural stabilities will be presented.