Realization of ferromagnetic strain glass in all- d -metal Heusler NiCoMnTi alloys

All-d-metal Heusler alloys demonstrate unique advantages for practical applications owing to their ferromagnetic martensitic transformation and excellent mechanical properties. By adjusting the Co and Ti content and optimizing the material preparation process as well as heat treatment conditions, a ferromagnetic strain glass was achieved in all-d-metal Heusler Ni34Co16Mn33Ti17. Dynamic mechanical analysis reveals a frequency-dependent behavior obeying the Vogel–Fulcher relationship, with a freezing temperature of T0 = 226 K. Nanodomains of locally distorted structure were observed by transmission electron microscopy. Magnetic measurements indicate that the alloy is ferromagnetically ordered, with a Curie temperature Tc reaching 350 K, throughout the strain glass transition temperature range. In addition, benefiting from the stress-induced rearrangement of nanoscale martensitic domains, the material exhibits nearly linear superelasticity covering a broad temperature range from 323 to 160 K. This finding not only enriches the understanding of strain glass states in all-d-metal Heusler alloys but also provides a material platform for investigating strain glass-magnetism coupling.