High temperature strain glass in Ti50(Pd50−xCrx) alloy and the associated shape memory effect and superelasticity

Abstract

Strain glass has recently been reported in Ti50−xNi50+x (x≥1.5 at %) alloys and caused by the existence of point defects. This strain glass alloy, being nonmartensitic, exhibits shape memory effect (SME) and superelasticity (SE) around the freezing temperature T0. However, the T0 of Ti50−xNi50+x (x≥1.5 at %) strain glass alloy is very low (∼160 K), thus restricting its potential applications. In the present letter, we report a strain glass system, Ti50(Pd50−xCrx) (x≥9 at %), which has a significantly higher freezing temperature. It is based on a high-temperature martensitic system TiPd (with Ms∼810 K) and dopant Cr (as point defect). For Ti50(Pd40Cr10) strain glass, the freezing transition occurs at T0∼250 K, being close to the room temperature. Correspondingly, it exhibits SME and SE around its high T0. We further clarified that T0 of strain glass alloy is controlled by the martensitic transformation temperature Ms (i.e., martensite stability) of its corresponding host alloy without point defect. Our work provides insight into how to develop strain glass with desired T0 and the associated SME and SE for applications.