Synthesis of TiAl-(TiB2+Ti2AlC)Composites Using Combustion Reaction Processing,Following Arc-melting (特集 金属間化合物の粉体冶金と諸物性) Synthesis of TiAl-(TiB_2+Ti_2AlC) Composites Using Combustion Reaction Processing, Following Arc-melting
To enhance the negligible low-temperature strength and ductility and low high-temperature strength of titanium aluminides, TiAl-(TiB<SUB>2</SUB>+Ti<SUB>2</SUB>A1C) composites were made by the combustion reaction processing using Ti, Al, and B<SUB>4</SUB>C powders, and homogenized by arc melting. The alloy composition included Ti<SUB>52.2</SUB>A1<SUB>45.6</SUB>(B<SUB>4</SUB>C)<SUB>2, 2</SUB> in at.%. The resulting composites had about 14 vol.% (TiB<SUB>2</SUB>+Ti<SUB>2</SUB>AIC) in the matrix TiAl with a lamellar structure of Ti<SUB>3</SUB>Al. In the homogenized specimens, such lamellar structures were not observed, therefore, the matrix after the homogenizing treatment consisted predominantly of the TiAl phase which is expected from the Ti-Al equilibrium phase diagram. On the other hand, smaller particles were visible in the matrix, and appeared to form in place of solutionizing lamellae. These particles have also identified as a Ti<SUB>2</SUB>A1C phase with an average particle size of about 100-200 run. This suggested that carbon atoms in the matrix, probably in the Ti<SUB>3</SUB>Al phase, formed carbide Ti<SUB>2</SUB>Al particles when the lamellar Ti<SUB>3</SUB>Al phase was disappeared during the homogenization treatment. It was found that the composite material has a high strength at both ambient and elevated (at 1173 K) temperatures ; about 900 and 500 MEN, respectively, and ambient-temperature ductility as large as 0.8% was obtained in bending.
粉体および粉末冶金 44(6), 535-541, 1997-06-15
Japan Society of Powder and Powder Metallurgy