Directional solidification of intermetallic Ti-46Al-2W-0.5Si alloy in alumina moulds

作者：Lapin J^*; Ondrus L; Nazmy M

来源：Intermetallics, 2002, 10(10): 1019-1031.

DOI：10.1016/S0966-9795(02)00119-X

• titanium aluminides, based on TiAl
• mechanical properties at ambient temperature
• crystal growth
• microstructure

The microstructure and mechanical properties of intermetallic Ti-46Al-2W-0.5Si (at.%) alloy directionally solidified in alumina moulds were studied. After directional solidification the microstructure consisted of regular alpha(2)- and gamma-lamellae, elongated 132 particles, Al2O3 particles and fine Ti5Si3 precipitates. Formation of transient cellular-dendritic structure was observed at the growth rates of 2.78 x 10(-6) and 5.56 x 10(-6) m/s. Higher growth rates ranging from 1.39 x 10(-5) to 1.18 x 10(-4) m/s resulted in a regular dendritic structure where the primary dendrite arm spacing decreased with increasing growth rate according to relationship lambda(1) alpha V-0.24. The interlamellar spacing decreased with increasing growth rate according to the relationship lambda alpha V-0.46. The volume fraction of Al2O3 particles increased with increasing temperature of the melt and reaction time. Increasing growth rate resulted in increasing microhardness and compression yield stress of DS ingots. A linear relationship between the microhardness and compression yield stress was determined. The yield stress increased with decreasing interlamellar spacing according to the Hall-Petch relationship.

• 出版日期2002-10