Shin'ichi Sato1, Ryuichiro Oshima2 and Zenji Nishiyama3
1Institute of Scientific & Industrial Research, Osaka University, Osaka
The effect of the Ms temperature on the lattice defects in martensite was studied by X-ray diffraction. Fe-Ni alloys with 10, 15 and 20 wt%Ni were chosen as the specimens having different Ms temperatures. The profiles of the Debye-Scherrer lines of martensites in three alloys, were taken with an X-ray diffractometer. Correction was made for the instrumental broadening, and the Fourier analysis was performed.
It is concluded from the results that: (1) The integral width of the martensite line decreases with increasing the Ms temperature. (2) The index-dependences of the broadening are the same for all the specimens examined. (3) The internal strain of the 110 direction in the martensite decreases with increase of the Ms temperature, whereas the effective domain size of that direction does not change so much.
The above results show that, even at a Ms temperature much higher than room temperature, considerable amounts of the lattice defect, including the stacking mistakes, are introduced during the martensitic transformation.
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