ANOMALOUS STRAIN RATE DEPENDENCE OF FLOW STRESS IN TiAl INTERMETALLIC COMPOUNDS

摘要

Plastic deformation of TiAI and TiAI-V intermetallic compounds has been studied by com-pression experiment at various temperatures and strain rates.Results show that the plasticdeformation in distinct temperature range is principally controlled by the mechanisms ofPeierls-Nabarro,cross slip and creep of dislocations.For TiAI-V alloy deformed at a rangeof 600—700 K,the negative strain rate dependence of flow stress was observed,i.e.,the morethe plastic strain is.the more the negative dependence will be.A possible mechanism of theanomaly could be interpreted by thermal activation of dislocation cross slipping.The effects oftemperature and strain rate on work-hardening exponent were also studied and discussed.