Novel B19′ strain glass with large recoverable strain

Abstract

We report a strain glass state (B19\ensuremath{'} strain glass) in a Ni-rich TiNi shape memory alloy produced by cold rolling. As compared to previously reported strain glasses, this strain glass state has outstanding properties including quasilinear superelasticity with a large recoverable strain (\ensuremath{\sim}4%), and slim hysteresis and high strength (\ensuremath{\sim}1.0 GPa) over a wide temperature range (\ensuremath{\sim}200 K). The existence of the B19\ensuremath{'} strain glass state is confirmed by (i) frequency dispersion of storage modulus, (ii) continuous decrease of electrical resistivity, and (iii) continuous growth of B19\ensuremath{'} nanodomains upon cooling. This study proves that the effect of defect strength on the creation of a strain glass state is in parallel to the effect of cooling rate on the creation of a structural glass, e.g., any strain crystal (i.e., martensite) can be turned into a strain glass if strong enough defects could be engineered.