Papers by Keyword: Snoek-Type Relaxation

Abstract: The internal friction of Ti-35.4Nb-0.05C (wt.%) was investigated using a dynamic mechanical analysis (DMA) Q800 from TA Instruments. It has been shown that a relaxational peak is observed in the water-quenched Ti-35.4-Nb-0.05C alloy on tanδ-temperature curve. The activation energy and pre-exponential factor of the peak are H_q=1.82±0.1 eV and τ_0q=1.7×10^-19±1 s, respectively. The activation energy value is a little larger than that of the water-quenched Ti-35.4-Nb alloy. The peak height is decreased compared with the water-quenched Ti-35.4-Nb alloy.

Abstract: The effect of ternary alloying elements on the oxygen Snoek-type relaxation in the Ti-24Nb-2X-1.7O alloys (X = Al, Sn, Cr, Mn, Fe) was investigated. The dipole shape factor (δλ) of the Snoek-type relaxation was figured out for each ternary alloy based on the measured damping peak with the variable temperature. The value of δλ in the Ti-Nb-Al alloy was the highest among the present ternary alloys. It was found that δλ increased with the decreasing lattice constant as well as the decreasing valence electron number per atom (e/a) and came to a maximum value when the e/a value was around 4.24, which defined the β phase boundary. Therefore, decreasing the lattice constants and the e/a value as largely as possible with alloying elements in the β-Ti alloys is one of the feasible ways to increase δλ and to design the high damping Ti alloys.

Abstract: Measurements of the H-induced damping peak in Zr-based multi-component metallic glasses, with different tendency to quasicrystal formation, are added to previous reviews of the properties of this damping peak in metallic glasses, and also compared to Ti-Zr-Ni quasicrystals. The results, mainly discussed in terms of a Snoek-type relaxation mechanism for both structure types, indicate a negative correlation between the degree of icosahedral order and the temperature of the damping peak, so that improved damping properties of hydrogen-absorbing bulk metallic glasses can apparently be expected from stronger deviations from icosahedral short-range order.