High-temperature near-equiatomic TiNi strain glass

Strain glasses (STGs) exhibit many unique properties not available in their counterparts of martensites and have found applications in cutting-edge space technology. However, the strain glass transition temperature Tg is commonly too low to enrich applications, especially in prototypical TiNi-based shape-memory alloys (SMAs). Here we report a surprising finding of strain glass in Ti50.1Ni49.9 alloys with high Tg ∼290 K, which is the highest among existing TiNi STGs. It was achieved via a simple method of slight annealing at 573 K for 15 s on cold-rolled high Ms (martensitic transformation temperature) Ti50.1Ni49.9 SMAs. As a result, this near-equiatomic TiNi strain glass caused by cold-rolling-induced dislocations can inherit the high-Ms of Ti50.1Ni49.9 SMA and possess high Tg, manifested by a weak transition temperature decrease with cold-rolling reduction rate in the phase diagram.