Hydrogen internal friction peak in amorphous Zr-Cu-Al-Si alloys

The hydrogen internal friction peak (HIFP) in amorphous (a-) Zr 60 Cu 40-y Al y (y = 0, 10), a-Zr 50 Cu 50 , a-Zr 40 Cu 60 and a-Zr 40 Cu 50-x Al 10 Si x (x = 0, 1, 3) are studied to pursue a high-strength and high-damping performance as well as the underlying process for the HIFP in a-alloys. The tensile strength, σ f , of a-Zr 60 Cu 30 Al 10 , a-Zr 40 Cu 50 Al 10 and a-Zr 40 Cu 49 Al 10 Si 1 increases from about 1.5 GPa to 2 GPa with increasing hydrogen concentration, C H , to 20 at%. One part of a-Zr 60 Cu 30 Al 10 , a-Zr 40 Cu 50 Al 10 and a-Zr 40 Cu 49 Al 10 Si 1 specimens show a very high HIFP beyond 3 × 10 -2 in the as hydrogen charged state, where the hydrogen induced structural relaxation (HISR) proceeds above room temperature. A maximum value of the HIFP, Q -1 p , after the HISR shows a moderate increase with increasing C H , about I x 10 -2 at C H of 10 at% The combination of σ f and Q -1 p data indicates that a-Zr 60 Cu 40 Al 10 (H), a-Zr 40 Cu 50 Al 10 (H) and a-Zr 40 Cu 49 Al 10 Si 1 (H) after the HISR are potential materials with a high-strength and high-damping performance. The peak temperature of the HIFP, Tp, at 10 at%H is 309 K, 270 K and 220 K with the measurement frequency of about 200 Hz for a-Zr 40 Cu 49 Al 10 Si 1 , a-Zr 40 Cu 50 Al 10 and a-Zr 60 Cu 30 Al 10 , respectively. It is noted that Tp found for a-Zr 40 Cu 49 Al 10 Si 1 shows a breakthrough for an elevation of T p of the HIFP in a-alloys, and that a composite material composed of these a-alloys can serve a high-damping performance in a wide temperature range or a wide frequency range. For the underlying process of the HIFP, the Q -1 p vs. C H data shows a camel's humps like change for a-Zr 50 Cu 50 and a-Zr 40 Cu 60 , suggesting that only one part of hydrogen atoms can contribute to the HIFP. In contrast, Q -1 p shows a monotonous increase with increasing C H for C H below 20 at% for a-Zr 60 Cu 40-y Al y (y = 0, 10) and a-Zr 40 Cu 50-x Al 10 Si x (x = 0, 1, 3), suggesting that most of hydrogen atoms are associated with the HIFP in the a-alloys. For the relaxation parameters of the HIFP, values of 1/τ 0 ) fall in the range expected for a simple relaxation process for a-Zr 60 Cu 40-y Al y (y = 0, 10) and a-Zr 40 Cu 50-x Al 10 Si x (x = 0, 1, 3), but are extremely high for a-Zr 50 Cu 50 and a-Zr 40 Cu 60 , where τ 0 denotes the pre-exponential factor of the relaxation time. These results are discussed in the light of the amorphous structures in the a-alloys.