Temperature memory effect induced by incomplete transformation in TiNi shape memory alloy

摘要

Temperature memory effect can be induced by incomplete transformation upon either heating or cooling in TiNi shape memory alloys (SMAs). An incomplete cycle on heating (ICH) of shape memory alloy arrested at a temperature between A_s and A_f induce a kinetic stop slight higher than the arrested temperature in the next complete transformation cycle. An incomplete cycle on cooling of a shape memory alloy arrested at a temperature between M_s and M_f induce an increase of the transformation heat of the reverse transformation with a decrease in the arrested temperature in the following heating for a sample without R-phase transformation. And for a sample with R-phase transformation, when the stop temperature arrested in the temperature range between R_f and M_s, the heat flow detected upon following heating only shows one endothermic peak. With decreasing arrested temperature T_s to the temperature range between M_s and M_f. two endothermic peaks can be found upon the following heating. With decreasing arrested temperature T_s the transformation heat of the first peak decreases and that of the second peak increases.