ANOMALOUS STRAIN RATE DEPENDENCE OF FLOW STRESS IN TiAl INTERMETALLIC COMPOUNDS
TiAl金属间化合物反常应变速率效应的研究

Plastic deformation of TiAl and TiAl-V intermetallic compounds has been stu- died by compression experiment at various temperatures and strain rates. Results show that the plastic deformation in distinct temperature range is principally controlled by the mechanisms of Perierls-Nabarro, cross slip and creep of dislocation. For TiAl-V alloy deformed at a range of 600--700 K, the negative strain rate dependence of flow stress was observed, i. e., the more the plastic strain is, the more the negative dependence will be. A possible mechanism of the anomaly could be interpreted by thermal activation of dislocation cross slipping. The effects of tempera- ture and strain rate on work-hardening exponent were also studied and discussed.