T. Waitz et al. Acta Materialia 52(2004)137-147 200nm 200nm L H ⊙ 5nm g Fig. 1. Ni-50.3at %Ti after HPT deformation; strain S=6.7.(a) TEM 0.3at %Ti after HPt deformation; strain S= 7.3.(a) TEM bright field image. The amorphous matrix contains retained nano- ous matrix contains a volume fraction als showing dark contrast. P marks a coarse particle of the Ti2Ni of retained nanocrystals of less than about I %.(b) Crystallites having a lattice.(b) TEM dark field image of the heterogeneously distributed diameter of less than about 15 nm she ystallites showing bright contrast(H and L mark areas containing a corresponding TEM dark field image. H marks a higher density of high and low density of them).(c) In the diffraction pattern broad nanocrystals whereas in the area marked L there are almost no fuse rings of the amorphous phase are superimposed with rings nanocrystals. (c)Sa diffraction pattern showing broad diffuse rings of containing B2 and B19 diffraction spots of the nanocrystallites. he amorphous phase having radii that correspond to the length of the diffraction vectors(1 10),(211>and(220) of the B2 latticeFig. 2. Ni–50.3at.%Ti after HPT deformation; strain S ¼ 7:3. (a) TEM bright field image. The amorphous matrix contains a volume fraction of retained nanocrystals of less than about 1%. (b) Crystallites having a diameter of less than about 15 nm show up as bright spots in the corresponding TEM dark field image. H marks a higher density of nanocrystals whereas in the area marked L there are almost no nanocrystals. (c) SA diffraction pattern showing broad diffuse rings of the amorphous phase having radii that correspond to the length of the diffraction vectors h110i, h211i and h220i of the B2 lattice. Fig. 1. Ni–50.3at.%Ti after HPT deformation; strain S ¼ 6:7. (a) TEM bright field image. The amorphous matrix contains retained nano￾crystals showing dark contrast. P marks a coarse particle of the Ti2Ni lattice. (b) TEM dark field image of the heterogeneously distributed crystallites showing bright contrast (H and L mark areas containing a high and low density of them). (c) In the diffraction pattern broad diffuse rings of the amorphous phase are superimposed with rings containing B2 and B190 diffraction spots of the nanocrystallites. T. Waitz et al. / Acta Materialia 52 (2004) 137–147 139