Published online by Cambridge University Press: 10 February 2011
The 45Ni50Ti5Cu shape memory alloy exhibits one single thermoelastic martensitic transformation from the parent B2 phase to monoclinic B19’and looks as an appealing system to be used for the two way memory effect (TWME). First results, appeared in literature, on the TWME in 45Ni50Ti5Cu indicate that in this alloy high figures for the two way strain can be obtained. The prestrain method is here investigated to imprint the TWME in a 45Ni50Ti5Cu alloy: a pseudoplastic deformation higher than the reorientation strain is applied in martensite, followed, after unloading, by a recovery of the one-way strain by heating to 110°C. The two way memory strain is detected in the following thermal cycle. Results show the two way memory strain can be imprinted in just one cycle, but it can even considerably be increased by repeating the procedure: the highest figure for the two way memory strain is however obtained whenever a plastic unrecoverable strain is accumulated in the specimen in some prestraining cycles. Often the maximum two way strain is of the same order as the plastic strain and the former decreases with the increase of the latter.