Evidence for Strain Glass in the Ferroelastic-Martensitic SystemTi50−xNi50+x

We report here “strain glass,” a new glassy phenomenon in ferroelastic-martensitic system of Ni-rich intermetallic ${\mathrm{Ti}}_{50-x}{\mathrm{Ni}}_{50+x}$ ($x>1$), where local strain is frozen in disordered configuration below a critical temperature $T_g$. The ac elastic modulus shows a minimum at $T_g$, which exhibits logarithmic frequency dependence following Vogel-Fulcher relationship, and the corresponding internal friction shows a frequency-dependent peak located at a lower temperature. In situ high-resolution transmission electron microscopy observations reveal uncorrelated nanoclusters of martensiticlike phase, randomly frozen in the otherwise untransformed parentlike matrix. Being parallel to spin glass and relaxor, strain glass may shed new light on the fundamental physics of glass and lead to the discovery of novel properties.