Negative thermal expansion arrest point memory effect in TiNi shape memory alloy and NbTi/TiNi composite

A pre-strained TiNi wire shows an unusual turning point on its strain–temperature trajectory in the thermal cycle subsequent to one incomplete reverse transformation. This turning point has a close relation with the previous arrest temperature and the corresponding arrest strain, which can be regarded as a memory of the arrest strain–temperature point. We name it as negative thermal expansion arrest point memory effect. Furthermore, to acquire larger operational temperature range of this effect, a novel NbTi/TiNi composite is introduced.