Novel B19′ strain glass with large recoverable strain

Abstract

We report a strain glass state (B19′ 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 (∼4%), and slim hysteresis and high strength (∼1.0 GPa) over a wide temperature range (∼200 K). The existence of the B19′ strain glass state is confirmed by (i) frequency dispersion of storage modulus, (ii) continuous decrease of electrical resistivity, and (iii) continuous growth of B19′ 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.