The B2-B19-B19 ' transformation behaviour in Ti-(45-x)Ni-5Cu-xV alloys

초록

Transformation behaviour, shape memory characteristics and superelasticity of Ti-(45-x)Ni-5Cu-xV(at.%) (x = 0.5-2.0) alloys were investigated using different techniques. The B2-B19' transformation occurs when V content is less than 1.0 at.%, above which the B2-B19-B19' transformation occurs. The temperature gap between M-s' (the B2-B19 transformation start temperature) and M-s (the B19-B19' transformation start temperature) increased from 8 to 22K with increasing V content from 1.0 to 2.0 at.%. V content dependence of M-s' (the B2-B19 transformation start temperature) was 20Kat.%(-1). One-stage elongation occurred in Ti-44.5Ni-5.0Cu-0.5V and Ti-44.0Ni-5.0Cu-1.0V alloys, while two-stage elongation occurred in Ti-43.5Ni-5.0Cu-1.5V and Ti-43.0Ni-5.0Cu-2.0V alloys. Transformation hysteresis decreased from 16 to 12K with increasing V content from 0.5 to 2.0%. The superelastic recovery ratio increased from 65.0 to 86.1% with increasing V content from 0.5 to 2.0%.

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