DEFORMATION-BEHAVIOR IN L1(0)-TYPE FEPT COMPOUND

Compressive deformation of L1(0),-type FePt compound was performed fro m room temperature to 873 K in a protective atmosphere. The results sh ow that the yield stress decreases monotonically with increasing tempe rature. The strain rate sensitivity parameter changes with temperature similarly to that of silver and copper, and does not exhibit a ''near -zero'' phenomenon. This indicates that the temperature-dependent defo rmation in the studied temperature range is similar to that of f.c.c. metals, and very different from that of L1(0) TiAl. The deformation st ructure investigated by transmission electron microscopy shows that tw inning and slip are the two major deformation mechanisms. The twin sys tem was identified as {111}<112] type. No pseudotwinning was found in this alloy as was the case in TiAl. Two different types of dislocation s with Burgers' vectors of(1/2)<110] and <101] were identified. The mo rphology of these dislocations indicates that the dislocations do not experience a high Peierls' stress as seen in TiAl. No self-dissociatio n of superdislocations or antiphase boundary cross-slip onto cube plan es was observed under weak beam conditions.