| Popis: |
Morphologies resulting from the transformation of austenite to martensite during deformation of an Fe-21Ni-0.6C alloy are described. Samples were deformed either by conventional quasistatic tension loading, by high-strain-rate inertial tension loading, or by flyer-plate, compression shock loading. The various martensites observed are classified either as stress-assisted or strain-induced martensite. The stress-assisted martensite is characteristic of the plate martensite formed by lowering the temperature below the Ms of the alloy. The strain-induced martensite, which forms only during plastic deformation, appears as laths or platelets, but with different morphologies in the tension-loaded and shock-loaded samples. In the tension-loaded, deformed samples, the laths are clustered within the deformation bands. In the shock-loaded samples, arrays of relatively thin, long laths, where observed, aligned parallel to the {111}γ twin boundaries of the more homogeneously deformed parent austenite. Where both martensites are present, the strain-induced martensite appears to have formed prior to the stress-assisted martensite. Differences in morphology between the shock-loaded and nonshock-loaded samples are ascribed to differences in the extent of dislocation generation and movement. |
