Abstract
The ω-phase transformation and β-phase stability in Ti–xNb (28 ≤ x ≤ 40 at%) single crystals were investigated using electrical resistivity measurements, transmission electron microscopy (TEM) observations, and specific heat measurements. The crystal for x = 28 exhibits distinct anomalous negative temperature dependence of the resistivity coefficient and thermal hysteresis accompanied by the presence of the athermal ω-phase and β-phase lattice modulation. Although the crystal for x = 30 appears in the β-phase lattice modulation, it does not exhibit a clear negative temperature dependence of the resistivity coefficient or the athermal ω-phase. The crystal of x = 30 also shows a relatively high absolute value of resistivity at 15 K among the crystals for 28 ≤ x ≤ 40 and a low Debye temperature in a normal conductive state. The crystal for x = 30 that shows the lattice modulation, high resistivity, and low β-phase Debye temperature correspond to the low stability of the β-phase. Moreover, the stability strongly depends on the Nb content of the binary Ti–Nb crystal.
