Abstract
Metal-hydrogen systems have attracted intense interest for diverse energy-related applications. However, metals usually reduce their ductility after hydrogenation. Here, we show that hydrogen can take the form of nano-sized ordered hydrides (NOH) homogeneously dispersed in a stable glassy shell, leading to remarkable enhancement in both strength and ductility. The yield strength is enhanced by 44% and the plastic strain is substantially improved from almost zero to over 70%, which is attributed to the created NOH and their interplay with the glassy shell. Moreover, the hydride-glass composite GdCoAlH possesses a giant magnetic entropy change (−ΔSM) of 18.7 J kg−1K−1 under a field change of 5 T, which is 105.5% larger than the hydrogen-free sample and is the largest value among amorphous alloys and related composites. The prominent ΔSM-ductility combination overcomes the bottlenecks of amorphous alloys as magnetic refrigerants. These results provide a promising strategy for property breakthrough of structural-functional alloys.
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Introduction
The interaction between hydrogen and metals is a topic of great significance in materials science. With increasing attention on hydrogen, an energy carrier of the future, hydrogen-metal systems have been intensively explored for various energy-related applications, such as hydrogen storage and sensing, rechargeable batteries, catalysis, refrigeration, and so on1,2,3. On the other hand, many metals and alloys suffer from hydrogen embrittlement4,5. Hydrogen embrittlement becomes a critical issue in many industrial applications of various alloys, including high-strength steels, aluminum alloys, titanium alloys, and magnesium alloys, etc., and thus has drawn much research attention over 100 years4,5,6. Although several mechanisms were proposed for the crystalline metals/alloys-hydrogen systems, the nature of hydrogen embrittlement is not well understood except for a few Zr, Ti metals/alloys (where the hydride formation leads to embrittlement)6. It was found that amorphous alloys (AMAs) may show better resistance to hydrogen embrittlement than crystalline alloys, but they become rather brittle above a critical hydrogen concentration as well7,8,9. Thus, it is widely and urgently needed to develop advanced hydrogen-metal systems combining excellent functional and mechanical performances.
Different from conventional metals and alloys, AMAs have a unique disordered atomic structure with no grain boundaries and dislocation. This endues AMAs with high strength, improved wear resistance, excellent soft magnetic and anti-corrosion properties, and so on10,11,12. Nevertheless, the AMAs have several inherent shortcomings impeding their development and wider applications. Besides the restricted sample size imposed by the critical cooling rate for glass formation and limited working temperature below the glass transition temperature, their poor plasticity at ambient temperature and propensity for catastrophic failure originating from severe plastic-strain localization in shear bands (SBs) are critical drawbacks11, largely undercutting their structural and functional utilization. Moreover, some functional properties cannot be effectively enhanced and even may be degraded through the amorphization of alloys, such as magnetocaloric performances. Although the AMAs take the advantages of magnetic softness, large resistivity leading to smaller eddy current loss, and broad magnetic entropy change (ΔSM) peak as promising magnetic refrigerant13,14, they suffer from the drawback of low-to-medium ΔSM owing to the amorphous nature with second-order magnetic transition. Among various AMA systems, the Gd-based AMAs showing much larger maximum ΔSM (\(-\triangle {S}_{M}^{{pk}}\)) than the Pd-, Fe-, Ni- and Co-based AMAs13,1f–h, which show homogenous distributions of the Gd, Al, and Co elements and do not correlate apparently with heterogeneity seen from the HAADF-STEM image. Thus, the contrast variation in the STEM image mainly arises from the density fluctuation, which is an intrinsic feature of AMAs.
a SEM image of the amorphous powders with a diameter of 25–30 μm. b TEM image and c SAED pattern of the powder. d HRTEM image of the powder. e–h High-resolution HAADF image and corresponding EDS map**s of Al, Co, and Gd elements. i XRD patterns of the GdCoAl powders with different diameters less than 70 μm and the GdCoAlH powder with the saturated absorption of hydrogenation. j DSC curves of the GdCoAl and GdCoAlH powders at the heating rate of 20 K/min. The inset displays the curve of hydrogenation dynamics.
AMAs have a disordered structure and a wide spectrum of atomic-packing heterogeneities, which provide an infinity of interstitial sites for hydrogen occupation8. For the present Gd55Co17.5Al27.5 AMA containing Gd element with a strong affinity for hydrogen, a high hydrogen concentration and formation of hydride in the alloy can be expected after hydrogenation. Figure 1i shows the X-ray diffraction (XRD) patterns of the as-prepared Gd55Co17.5Al27.5 and hydrogenated powders (GdCoAl and GdCoAlH for short, respectively). The broad diffraction maxima of the pattern shifts to lower 2θ after hydrogenation, indicating a volume expansion as observed in other AMAs29,30. The differential scanning calorimetry (DSC) curves of the GdCoAl and GdCoAlH powders are presented in Fig. 1j. Distinct endothermal events corresponding to glass transition and exothermal event resulting from crystallization are observed for the as-prepared powders. And the onset temperatures for glass transition and crystallization are determined to be 600 and 670 K, respectively. A large supercooled-liquid region of 70 K, indicating its excellent glass-forming ability. After hydrogenation, the crystallization temperature decreases slightly to around 667 K. Due to the overlap between the glass transition and hydrogen desorption (starting around 600 K), the onset temperature of the glass transition cannot be determined accurately. The existence of a supercooled-liquid region and crystallization peak after hydrogenation indicates that there remains a significant amount of amorphous phase.
To explore the interaction between hydrogen and Gd-based AMA in more details, the atomic structure of the hydrogenated alloy was further investigated by special aberration-corrected high-resolution TEM (HRTEM) and HAADF-STEM. The HRTEM image indicates that the sample possesses a unique structure with some structurally ordered regions with several nanometers in size embedded in the amorphous matrix (Fig. 2a). This can be further seen from the inverse Fourier transform (IFT) image (Fig. 2b) of region A in Fig. 2a, in which lattice stripes (white area) were observed. Moreover, the SAED pattern reveals the presence of the GdH2 phase (Fig. 2c), which implies that the ordered region may be the GdH2 clusters. The STEM image indicates more clearly that many nanosized (2–5 nm) ordered hydrides (NOH) are embedded homogeneously in the amorphous matrix (Fig. 2d). The amorphous matrix serves as a shell with a thickness of 1–4 nm, which wraps up the NOH structure. And the concentration profiles of Gd, Al, and Co elements (Fig. 2e) along the diagonal line of the STEM image in Fig. 2d show a random fluctuation without any correlation with the contrast variation observed in Fig. 2d. This means that there is no apparent concentration difference of Gd, Al, and Co between the NOH and amorphous matrix. High-resolution STEM (HRSTEM) has been carried out to further characterize NOH regions (Fig. 2f). The NOH regions can be observed clearly, which comprise several ordered clusters. Element map**s in Fig. 2g–i present a homogenous distribution, which agrees with the results shown in Fig. 2e. This means that hydrogenation does not induce aggregation of elements, and the hydrogen atoms just occupy the interstitial sites and most of them interact with their neighboring Gd atoms to form NOH. Electron energy loss spectroscopy (EELS) was further used to characterize the structurally ordered regions. Figure 2j shows the EELS spectra for the typical ordered region B and disordered region C. A peak at 13.6 eV from the hydrogen K edge is clearly observed for region B (NOH) in Fig. 2f, which is absent for region C. In a word, the Gd-based SNDP-GH material comprises the randomly distributed GdH2 clusters of around 3.6 nm in diameter and the remaining amorphous shell with a thickness of 1–4 nm. The similar structures were also constructed in the GdNiAl and DyCoAlSi AMAs via hydrogenation (Supplementary Fig. 1).
a HRTEM image and b the further magnification of region A (after inverse Fourier transform) in a, showing the local ordering structures induced by hydrogenation. c Corresponding SAED pattern. d, e HAADF image and element fluctuation along the diagonal. f–i HRSTEM image and corresponding EDS map**s of Gd, Co, and Al elements. j EELS curves of the regions B (local ordering structure) and C (adjacent amorphous structure) in (f).
Mechanical properties
The brittleness of AMAs arising from a lack of crystalline defects is one of the critical problems hindering their wider practical applications as structural and/or functional materials, including magnetic refrigerant. It is well-known that many crystalline alloys are subjected to hydrogen embrittlement4,5. Hence, it is of interest to explore the mechanical performance of this hydrogenated alloy with a dual-phase structure. Since powders were investigated in the present study, we carried micro-compression tests on the micropillars fabricated from the powders. Figure 3a compares the compressive engineering stress-strain curves of the pillars with a diameter of 500 nm and a height of 1 μm for the as-prepared and hydrogenated alloys. The GdCoAl sample has a yield strength of 2.5 GPa without any plasticity, indicating its intrinsic brittleness. In contrast, the hydrogenated sample shows a yield strength of 3.6 GPa and a plastic strain of over 70%, reversing the hydrogen embrittlement in many metals and alloys. Larger size sample with 5 μm in diameter was also investigated and the result is shown in the inset of Fig. 3a. A large strain of over 55% (without fracturing) is still observed, illustrating that such a brittle-to-ductile transition does not arise from the size effect. Figure 3b,c shows the morphology images after compression of the GdCoAl and GdCoAlH pillars with a diameter of 500 nm. The GdCoAl pillar shows the features of brittle fracture. In contrast, the GdCoAlH pillar was compressed into a flake without fracturing and obvious SBs are observed. The multiple SBs can be seen more clearly for the GdCoAlH pillar with 5 μm in diameter (Fig. 3e). Furthermore, we investigated different systems (GdNiAl and DyCoAlSi), and similar brittle-to-ductile transition induced by hydrogenation is observed (Supplementary Fig. 2). Figure 3f shows the excellent mechanical performances of the several hydrogenated rare earth (RE)-based AMAs compared with their hydrogen-free counterparts and other typical RE-based bulk metallic glasses (BMGs). It can be seen clearly that the SNDP-GH nanostructure enhances greatly both the strength and plasticity, overcoming the strength-ductility trade-off in AMAs. Meanwhile, these results imply that creating an SNDP structure could be an effective strategy to overcome the hydrogen embrittlement of many metal-hydrogen systems.
a Engineering stress-strain curves of the pillars with a diameter (Φ) of 500 nm and height of 1 μm. The inset shows the stress-strain curves of the GdCoAlH pillar with a diameter of 5 μm and height of 10 μm. b, c Morphology images after compression of GdCoAl and GdCoAlH pillars with a diameter of 500 nm. d, e Morphology images of the GdCoAlH pillar with a diameter of 5 μm before and after compression. f Summary of the stress versus strain for the typical rare earth-based amorphous micropillars and BMGs, the data of this study are also added.
Magnetic transition and magnetocaloric properties
Next, we investigated the effect of hydrogenation on the magnetic transition and magnetocaloric properties. Figure 4a presents the temperature dependence of the zero-field-cooling (ZFC) and field-cooling (FC) magnetization of the GdCoAl and GdCoAlH alloys. The same temperature dependence of the ZFC and FC curves is observed for GdCoAl, indicating a typical ferromagnetic transition. In contrast, for the GdCoAlH alloy, both the ZFC and FC magnetization curves show a peak around the Néel temperature TN, below which bifurcation appears between the FC and ZFC branches. From the Curie-Weiss fit of the magnetic susceptibility far above the magnetic ordering temperature (Supplementary Fig. 4a), the paramagnetic Curie temperatures are determined to be 107 K and −27 K for the GdCoAl and GdCoAlH alloys, respectively. This verifies that ferromagnetic and antiferromagnetic exchange interactions dominate the magnetic structure in GdCoAl and GdCoAlH, respectively. The AC susceptibility χ (real part) curves under different frequencies from 13 to 9673 Hz are almost the same (Supplementary Fig. 4b), indicating further the antiferromagnetic transition nature, which is different from the obvious change of the peak position and intensity with increasing frequency in the Ho- and Dy-based AMAs showing spin-glass-like behavior19 (Supplementary Fig. 7a). The antiferromagnetic-to-paramagnetic transition arises from the GdH2 hydride31. Besides, hydrogenation does not change the magnetic soft nature of the alloy, as indicated in Fig. 4b, which is beneficial for magnetic cooling applications.
a Temperature dependence of magnetization (M). b Magnetic hysteresis loops measured at 5 K. c Temperature dependence of magnetic entropy change (ΔSM) under the maximum applied field of 2 and 5 T. d Summary of maximum magnetic entropy change (\({-\triangle S}_{M}^{{pk}}\)) (magnetic field change ΔH = 5 T) versus the peak temperature (Tp) for the typical Gd-based amorphous and dual-phase alloys, as well as the value of GdCoAlH. e Comparison of the mechanical (ultimate strength σu, yield strength σy, and strain ε) and magnetic properties (\(-\triangle {S}_{M}^{{PK}}\), Tp, coercivity Hc, and relative cooling power RCP) of the GdCoAl and GdCoAlH alloys and representative crystalline Gd and GdSiGe alloys.
From the isothermal magnetization curves (Supplementary Fig. 4c, d), the ΔSM of the alloys can be evaluated from the Maxwell relations. As presented in Fig. 4c, the hydronated alloy shows a giant \(-\triangle {S}_{M}^{{pk}}\) of 18.7 J kg−1 K−1 under a field change of 5 T, which is comparable to that of the prototype giant-MCE material Gd5Si2Ge232,33 and is twice as large as that (9.1 J kg−1 K−1) of the GdCoAl AMA. A rescaled temperature \((\theta=(T-{T}_{p})/({T}_{r}-{T}_{p}))\) dependence of the normalized magnetic entropy change \({\varDelta S}_{M}/\triangle {S}_{M}^{{PK}}\) was analyzed to check the scaling behavior and illustrate the second-order nature (which is revealed from the Arrott-plot in Supplementary Fig. 4e, f)14, where Tp is the peak temperature of ΔSM, and Tr is the reference temperature (\({{\varDelta S}_{M}({T}_{r})/\triangle {S}_{M}^{{PK}}=}\) 0.7). As shown in the Supplementary Fig. 4i, all the MCE curves under different fields are collapsed into a single master curve for the GdCoAlH alloy with a dual-phase structure. To highlight the giant-MCE of the hydrogenated alloy, we compare present data with the \(-\triangle {S}_{M}^{{pk}}\) values under a field change of 5 T for various Gd-based AMAs and related dual-phase alloys All data needed to evaluate the conclusions in the paper are present in the paper and/or the supplementary information. Data were also available from the corresponding author upon request. Sheppard, D. A. et al. Metal hydrides for concentrating solar thermal power energy storage. Appl. Phys. A 122, 395 (2016). Huiberts, J. N. et al. Yttrium and lanthanum hydride films with switchable optical properties. Nature 380, 231–234 (1996). Züttel, A., Borgschulte, A. & Schlapbach, L. Hydrogen as a Future Energy Carrier (Wiley, 2008). Chen, Y. S. et al. Direct observation of individual hydrogen atoms at trap** sites in a ferritic steel. Science 355, 1196–1199 (2017). Scully, J. R., Young, G. A. & Smith, S. W. Gaseous Hydrogen Embrittlement of Materials in Energy Technologies (Elsevier, 2012). Dwivedi, S. K. & Vishwakarma, M. Hydrogen embrittlement in different materials: a review. Int. J. Hydrog. Energ. 43, 21603–21616 (2018). Jayalakshmi, S., Fleury, E., Leey, D. Y., Chang, H. J. & Kim, D. H. Hydrogenation of Ti50Zr25Co25 amorphous ribbons and its effect on their structural and mechanical properties. Philos. Mag. Lett. 88, 303–315 (2008). Granata, D., Fischer, E. & Löffler, J. F. Effectiveness of hydrogen microalloying in bulk metallic glass design. Acta Mater. 99, 415–421 (2015). Zhao, Y. K. et al. Effect of hydrogen on the yielding behavior and shear transformation zone volume in metallic glass ribbons. Acta Mater. 78, 213–221 (2014). Inoue, A. Stabilization of metallic supercooled liquid and bulk amorphous alloys. Acta Mater. 48, 279–306 (2000). Wang, W. H., Dong, C. & Shek, C. H. Bulk metallic glasses. Mat. Sci. Eng. R. 44, 45–89 (2004). Wang, W. H. Dynamic relaxations and relaxation-property relationships in metallic glasses. Prog. Mater. Sci. 106, 100561 (2019). Luo, Q. & Wang, W. H. Magnetocaloric effect in rare earth-based bulk metallic glasses. J. Alloy. Compd. 495, 209–216 (2010). Franco, V. et al. Magnetocaloric effect: from materials research to refrigeration devices. Prog. Mater. Sci. 93, 112–232 (2018). **a, L., Tang, M. B., Chan, K. C. & Dong, Y. D. Large magnetic entropy change and adiabatic temperature rise of a Gd55Al20Co20Ni5 bulk metallic glass. J. Appl. Phys. 115, 223904 (2014). Franco, V., Blazquez, J. S., Conde, C. F. & Conde, A. A Finemet-type alloy as a low-cost candidate for high-temperature magnetic refrigeration. Appl. Phys. Lett. 88, 042505 (2006). Zhu, R. W. et al. Magnetocaloric effect in Co-based amorphous alloy Co90Nb10Ta3. J. Magn. Magn. Mater. 484, 253–257 (2019). Shen, T. D., Schwarz, R. B., Coulter, J. Y. & Thompson, J. D. Magnetocaloric effect in bulk amorphous Pd40Ni22.5Fe17.5P20 alloy. J. Appl. Phys. 91, 5240–5245 (2002). Luo, Q., Zhao, D. Q., Pan, M. X. & Wang, W. H. Magnetocaloric effect of Ho-, Dy-, and Er-based bulk metallic glasses in helium and hydrogen liquefaction temperature range. Appl. Phys. Lett. 90, 211903 (2007). Luo, Q., Schwarz, B., Mattern, N. & Eckert, J. Giant irreversible positive to large reversible negative magnetic entropy change evolution in Tb-based bulk metallic glass. Phys. Rev. B 82, 024204 (2010). Luo, Q., Cui, J., Zhang, Z., Han, M. & Shen, B. Tuning nanoscale heterogeneity by non-affine thermal strain to modulate defect activation and maximize magnetocaloric effect of metallic glass. Mater. Des. 225, 111500 (2023). Bingham, N. S. et al. Excellent magnetocaloric properties of melt-extracted Gd-based amorphous microwires. Appl. Phys. Lett. 101, 102407 (2012). Fu, H., Zheng, Q. & Wang, M. X. Magnetocaloric effect contributed by in situ dual-phase structure in the Gd-Co-Al alloy. Appl. Phys. Lett. 99, 162504 (2011). Zheng, Q., Zhang, L. & Du, J. Magnetic entropy change in Gd95Fe2.8Al2.2 amorphous/nanocrystalline ribbons. Scr. Mater. 130, 170–173 (2017). Gorsse, S., Chevalier, B. & Orveillon, G. Magnetocaloric effect and refrigeration capacity in Gd60Al10Mn30 nanocomposite. Appl. Phys. Lett. 92, 122501 (2008). Shao, L. L. et al. Gamma relaxation in Dy-based metallic glasses and its correlation with plasticity. Scr. Mater. 222, 115017 (2023). Wang, Q. et al. Universal secondary relaxation and unusual brittle-to-ductile transition in metallic glasses. Mater. Today 20, 293–300 (2017). Shao, L. L., Xue, L., Luo, Q., Wang, Q. Q. & Shen, B. L. The role of Co/Al ratio in glass-forming GdCoAl magnetocaloric metallic glasses. Materialia 7, 100419 (2019). Fu, H., Zou, M. & Singh, N. K. Modification of magnetic and magnetocaloric properties of Dy–Co–Al bulk metallic glass introduced by hydrogen. Appl. Phys. Lett. 97, 262509 (2010). Shao, L. L. et al. Heterogeneous GdTbDyCoAl high-entropy alloy with distinctive magnetocaloric effect induced by hydrogenation. J. Mater. Sci. Technol. 109, 147–156 (2022). Bos, W. G. & Gayer, K. H. Rare earth hydrides. J. Nucl. Mater. 18, 1 (1966). Pecharsky, V. K. & Gschneidner, K. A. Giant magnetocaloric effect in Gd5(Si2Ge2). Phys. Rev. Lett. 78, 4494–4497 (1997). Provenzano, V., Shapiro, A. J. & Shull, R. D. Reduction of hysteresis losses in the magnetic refrigerant Gd5Ge2Si2 by the addition of iron. Nature 429, 853–857 (2004). Yuan, F., Du, J. & Shen, B. Controllable spin-glass behavior and large magnetocaloric effect in Gd-Ni-Al bulk metallic glasses. Appl. Phys. Lett. 101, 032405 (2012). Fu, H. & Zou, M. Magnetic and magnetocaloric properties of ternary Gd-Co-Al bulk metallic glasses. J. Alloy. Compd. 509, 4613–4616 (2011). Dong, Q. Y. et al. Large magnetic refrigerant capacity in Gd71Fe3Al26 and Gd65Fe20Al15 amorphous alloys. J. Appl. Phys. 105, 053908 (2009). Fu, H. et al. Table-like magnetocaloric effect in the Gd-Co-Al alloys with multi-phase structure. Appl. Phys. Lett. 104, 072401 (2014). Li, Z., Ding, D. & **a, L. Excellent magneto-caloric effect of a binary Gd63Ni37 amorphous alloy. Intermetallics 86, 11–14 (2017). Ma, Y. F., Yu, P. & **a, L. Achieving the best glass former in a binary Gd–Co alloy system. Mater. Des. 85, 715–718 (2015). Feng, J. Q. et al. Giant refrigerant capacity in Gd-based amorphous/nanocrsytalline composite fibers. Mater. Today Phys. 21, 100528 (2021). Vajda, P. Handbook on the Physics and Chemistry of Rare Earths (Elsevier, 1995). Wu, G. et al. Dual-phase nanostructuring as a route to high-strength magnesium alloys. Nature 545, 80–83 (2017). Sarac, B. & Schroers, J. Designing tensile ductility in metallic glasses. Nat. Commun. 4, 2158 (2013). Pauly, S., Gorantla, S., Wang, G., Kuehn, U. & Eckert, J. Transformation-mediated ductility in CuZr-based bulk metallic glasses. Nat. Mater. 9, 473–477 (2010). Sarac, B. et al. Origin of large plasticity and multiscale effects in iron-based metallic glasses. Nat. Commun. 9, 1333 (2018). Sun, B. A. & Wang, W. H. The fracture of bulk metallic glasses. Prog. Mater. Sci. 74, 211–307 (2015). This work was supported by the National Natural Science Foundation of China (Grant Nos. 52231005, 52301212, 51971061, 52101193, NSFC-NSAF, and U2330111), Natural Science Foundation of Jiangsu Province, China (BK20221473), and Guangdong Major Project of Basic and Applied Basic Research, China (Grant No. 2019B030302010). L.S., Q.L., and B.S. designed the research project; L.S., M.Z., L.X., J.C., and Q.Y. fabricated the samples and performed the magnetic and mechanical experiments and structural tests; Y.Z. performed the hydrogenation experiments; Q.L., H.K., and B.S. conceptualized and supervised the research; Q.L. and L.S. wrote the draft of the manuscript; W.W. contributed to the general discussion of the results. All authors commented on the manuscript. The authors declare no competing interests. Nature Communications thanks Ricardo Floriano and the other, anonymous, reviewer for their contribution to the peer review of this work. A peer review file is available. Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Shao, L., Luo, Q., Zhang, M. et al. Dual-phase nano-glass-hydrides overcome the strength-ductility trade-off and magnetocaloric bottlenecks of rare earth based amorphous alloys.
Nat Commun 15, 4159 (2024). https://doi.org/10.1038/s41467-024-48531-7 Received: Accepted: Published: DOI: https://doi.org/10.1038/s41467-024-48531-7Data availability
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