HIGH-STRAIN RATE DEFORMATION OF TI-48AL-2NB-2CR

The compressive deformation behavior of Ti-48Al-2Nb-2Cr in the duplex microstructural morphology has been studied at strain rates of 0.001 a nd 2000 s(-1) over the temperature range from -196 to 1100 degrees C. The yield stress for the duplex microstructure is strain rate sensitiv e at 25 degrees C and increases with temperature from 500 to 1100 degr ees C at a strain rate of 2000 s(-1). TEM investigations revealed that deformation occurs in gamma-TiAl by means of {111}[112] twinning, 1/2 [110] slip and [101] superdislocations under all conditions depending on the orientation of the grain with respect to the deformation axis. Optical metallography revealed that twinning increases with increasing strain rate. The flow stress anomaly is discussed in reference to the dislocation substructure in gamma-TiAl.