| Transformation behavior and shape memory characteristics in Ti-(45-X)Ni-5Cu-X(Mo, Cr, Al)(at.%) alloys were investigated by means of differential scanning calorimetry, X-ray diffraction and thermal cycling tests under a constant load. The substitution of Mo, Cr and Al for Ni in Ti-45Ni-5Cu alloy induced the B2→B19 martensitic transformation prior to the B2→B19` transformation, and consequently Ti-(45-X)Ni-5Cu-X(Mo, Cr, Al)(at.%) alloys transformed in two stages; the B2→B19→B19`. The B2→B19 and the B19→B19` transformations were completely separated in Ti-(45-X)Ni-5Cu-X(Mo, Cr) alloys, whereas they were not done in a Ti-44.3Ni-5Cu-0.7A1 alloy without applied stress. The substitution of Mo, Cr and Al in a Ti-45Ni-5Cu alloy decreased transformation hysteresis and the residual elongation. The maximum recoverable elongation of Ti-(45-X)Ni-5Cu-X(Mo, Cr, Al) alloys was about 5%. |
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