Strain glass in defect-containing ferroelastic Ti₄₄Ni₅₁Nb₅ alloy

An abnormal phenomenon was investigated in Ti₄₄Ni₅₁Nb₅ alloy which exhibits an absence of martensite transformation and a negative temperature dependence of electrical resistivity with the temperature decreasing. X-ray diffraction (XRD) analysis shows the matrix phase keeps a B2 structure during cooling without a martensite transformation, and dynamic mechanical analysis displays a frequency-dependent AC modulus/loss anomaly at T_g according to Vogel-Fulcher relation. Simultaneously, transmission electronic microscope (TEM) analysis manifests the superlattice spots at near 1/3 commensurate position, implying an existence of strain nanodomains with an R-like structure. And above experiment results provide evidence for the “strain glass” transition in defect-containing ferroelastic Ti₄₄Ni₅₁Nb₅ alloy.