We investigated the deformation mechanisms of long period stacking ordered (LPSO) structures in an extruded Mg97Y2Zn1 (at%) alloy. Tensile deformation was performed in such a way that basal slip and kink band formation were inhibited. Slip trace analysis and transmission electron microscopy reveal a predominant activity of non-basal slip.

Microstructure evolution of a supersaturated solid solution Mg–2.2 wt%Nd alloy during aging at 240 °C for 6 h (stage I), at 295 °C for 3 h (stage II), and finally at 320 °C for 1 h (stage III) was studied by in situ synchrotron X-Ray diffraction. In stage I, diffraction from β1 (Mg3Nd, FCC) precipitates was observed after ~ 15 min. Evolution of the volume, size, and aspect ratio of β1 with the aging time were estimated from peak intensity and peak width analysis. In stage II, diffraction from β (Mg12Nd, tetragonal) precipitates was observed after ~ 36 min while β1 remained in the material. In stage III, the volume of β1 reduced substantially in relative to β. The identified precipitation sequence from the in situ aging experiment is supported by ex situ electron microscopy observations. β′, which had not been detected by synchrotron X-rays, was additionally found using transmission electron microscopy in the material by the end of aging stage I. Tension and hardness tests using specimens with different aging conditions were further performed to understand how different precipitates affect the strength and ductility of the Mg–Nd alloy.

•γ-Fe(Ni) nano powder was prepared via arc plasma evaporation of Fe–Ni mixture.•Mg2Fe(Ni)H6 was produced using coarse grained Mg and γ-Fe(Ni) nano powder.•Formation kinetics of Mg2FeH6 was improved using γ-Fe(Ni) as precursor.•The Mg2Fe(Ni)H6 has a “tangled nanowire” microstructure.•The Mg2Fe(Ni)H6 shows better hydrogen sorption properties over Mg2FeH6.In this work, Mg2Fe(Ni)H6 was synthesized under relatively mild conditions using precursors of coarse-grained Mg powder and Fe(Ni) composite containing γ-Fe(Ni) nano particles prepared through arc plasma method. The microstructure, composition, phase components and the hydrogen storage properties of the Mg–Fe(Ni) composite were carefully investigated. It is observed that the Mg2Fe(Ni)H6 formed from the Mg–Fe(Ni) composite has a “tangled nanowire” morphology with the wire diameter of 100–240 nm. In contrast, a typical columnar morphology was observed for the Mg2FeH6 produced from hydrogenation of coarse-grained Mg and pure α-Fe nano particles. A promotion effect on the synthesis of Mg2FeH6 is found for the utilization of γ-Fe(Ni) precursor instead of pure α-Fe. Indeed, γ-Fe(Ni) has the same fcc lattice as Mg2FeH6, which may remarkably shorten the diffusion distance of Fe during the formation of Mg2FeH6 from MgH2 and Fe. Meantime, the existence of Ni in Fe would catalyze the hydrogenation and influence the growing of Mg2Fe(Ni)H6/γ-Fe(Ni) interface, leading to the formation of Mg2Fe(Ni)H6 tangled nanowires. For hydrogen release, the peak desorption temperature of Mg2Fe(Ni)H6 is 593 K, which is 22 K lower than that of the Mg2FeH6. The absorption and desorption enthalpies of Mg2Fe(Ni)H6 were measured to be −68.8 ± 3.0 and 69.2 ± 3.2 kJ/mol H2, respectively. The improvements in both hydrogen sorption kinetics and thermodynamics can be attributed to destabilization effect of Ni substitution for Fe in the Mg2FeH6.Without any high-energy pre-treatments, Mg2Fe(Ni)H6, which has a “tangled nanowire” morphology, can be successfully synthesized under relatively mild conditions using precursors of coarse grained Mg powder and Fe(Ni) composite containing γ-Fe(Ni) nano particles. The improved hydrogen sorption kinetics and thermodynamics of Mg2Fe(Ni)H6 can be attributed to the destabilization of Mg2FeH6 through doping with Ni.

Rare-earth (RE) element addition can remarkably improve the mechanical properties of magnesium alloys through precipitation hardening. The morphology, distribution and crystal structure of precipitates are regarded as major strengthening mechanisms in the Mg-RE alloys. In order to understand the formation of precipitates during aging at 225 °C in a Mg-10Gd-3Y-0.4Zr alloy (GW103K) with high strength and heat resistance, a high-resolution transmission electron microscopy (HRTEM) was employed to characterize the microstructural evolution. It was found that three types of precipitates were observed in the alloy at the early stage, named as: single layer D019 structure, one single layer D019 structure and one layer of Mg, two parallel single layers (containing RE) and Mg layer in between, which was regarded as ordered segregation of RE, precursors to form β″ and β′ phase, respectively. Both of β″ and β′ phase were transformed from the precursors. It was also found that large size of β′ phase and the small size of β″ phase were constantly existent in the whole aging process. β′ phase played a major role in the strengthening of the GW103K alloys and the decrease of the hardness was caused by the coarsening of β′ phase.HRTEM images taken along <0001> zone axis and corresponding Fourier transform (FT) patterns showing three types of precipitates in the GW103K alloy aged at 225 °C for 0.5 h (a) Single layer D019 structure; (c) One single layer D019 structure and one layer of Mg; (e) Two parallel single layers (containing RE) and Mg layer in between; (b), (d), (f) Corresponding Fourier transform (FT) patterns for (a), (c), (e)

A systematic investigation has been performed on the hydrogen sorption properties of the Mg–X (X = Fe, Co, V) nano-composites co-precipitated from solution through an adapted Rieke method. It is found that the co-precipitated Fe, V or Co has high catalytic efficiency in enhancing the hydrogen sorption kinetics of nano-sized Mg. The Mg–V nano-composite shows faster hydrogen absorption kinetics than the Mg–Fe and Mg–Co nano-composites at lower temperatures. For instance, the hydrogen capacity within 2 h at 50 °C is 4.4 wt% for the Mg–V nano-composite, while for the Mg–Fe nano-composite it is 2.6 wt% and for the Mg–Co nano-composite it is 3.9 wt%. However, the hydrogenated Mg–Fe and Mg–Co nano-composites display significantly lower hydrogen desorption temperatures compared with the hydrogenated Mg–V nano-composite. The hydrogen desorption activation energies of the hydrogenated Mg–Fe and Mg–Co nano-composites are 118.1 and 110.1 kJ mol−1 H2, much lower than that of the Mg–V nano-composite (147.7 kJ mol−1 H2). High catalytic effectiveness of the co-precipitated Fe, Co or V depends not only on its intrinsic activity, but also on its distribution state, which may be entirely different from previous composites prepared through physical routes.

The present study was aimed at evaluating strain-controlled cyclic deformation behavior of a rare-earth (RE) element containing Mg-10Gd-3Y-0.5Zr (GW103K) alloy in different states (as-extruded, peak-aged (T5), and solution-treated and peak-aged (T6)). The addition of RE elements led to an effective grain refinement and weak texture in the as-extruded alloy. While heat treatment resulted in a grain growth modestly in the T5 state and significantly in the T6 state, a high density of nano-sized and bamboo-leaf/plate-shaped β′ (Mg7(Gd,Y)) precipitates was observed to distribute uniformly in the α-Mg matrix. The yield strength and ultimate tensile strength, as well as the maximum and minimum peak stresses during cyclic deformation in the T5 and T6 states were significantly higher than those in the as-extruded state. Unlike RE-free extruded Mg alloys, symmetrical hysteresis loops in tension and compression and cyclic stabilization were present in the GW103K alloy in different states. The fatigue life of this alloy in the three conditions, which could be well described by the Coffin–Manson law and Basquin’s equation, was equivalent within the experimental scatter and was longer than that of RE-free extruded Mg alloys. This was predominantly attributed to the presence of the relatively weak texture and the suppression of twinning activities stemming from the fine grain sizes and especially RE-containing β′ precipitates. Fatigue crack was observed to initiate from the specimen surface in all the three alloy states and the initiation site contained some cleavage-like facets after T6 heat treatment. Crack propagation was characterized mainly by the characteristic fatigue striations.

A Mg–Ti nano-composite has been co-precipitated from a tetrahydrofuran (THF) solution containing anhydrous magnesium chloride (MgCl2), titanium tetrachloride (TiCl4) and lithium naphthalide (LiNp) as the reducing agent. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and pressure-composition-temperature (PCT) techniques are used to characterize phase components, microstructure and hydrogen sorption properties of the composite. The co-precipitated Mg–Ti nano-composite contains nearly 1.0 wt% of Ti distributed homogeneously on the surface or inside Mg particles having an average particle size of about 50 nm. Orthorhombic γ-MgH2 phases and tetragonal γ-TiH2 phases are obtained when the Mg–Ti nano-composite is hydrogenated at 75 °C. PCT measurements reveal the superior hydrogen absorption property of the Mg–Ti nano-composite: its maximum hydrogen capacity can reach up to 6.2 wt% within 2 h at room temperature under a hydrogen pressure of 3 MPa. The activation energy for hydrogen absorption is determined to be 50.2 kJ mol−1 H2. The hydrogenation and dehydrogenation enthalpies of the nano-composite are calculated to be −73.0 ± 1.8 and 75.8 ± 4.7 kJ mol−1 H2, close to the standard values for Mg (−74.1 ± 2.9 kJ mol−1 H2). The catalytic effects from the co-precipitated Ti and the tetragonal γ-TiH2 formed during the hydrogenation process lead to extremely fast absorption kinetics at room temperature.

•We examine the hydrogenation thermodynamics in the Mg-13Y powder alloy.•We observe the microstructure evolution in the bulk alloy during hydrogenation.•Hydrogenation enthalpy of α-Mg containing yttrium is −42 kJ/mol H2 by experiment.•Enthalpy of the reaction (Mg24Y5 + 5H2 → 24 Mg + 5YH2) is −195 kJ/mol H2 by calculation.•The large Mg24Y5 phases could be hydrogenated into fine cuboid YH2 phases.The Mg-13Y bulk alloy was prepared by conventional casting process and the Mg-13Y powder was processed by ball milling using the casting alloy under the protection of argon. The hydrogenation thermodynamics, hydrogenation process and phase transitions were carefully investigated in the Mg-13Y powder alloy. It is shown that the Mg-13Y casting alloy consists of Mg24Y5 phase and α-Mg containing yttrium which have different hydrogenation enthalpies, −195 kJ/mol H2 (by calculation) and −42 kJ/mol H2 (by Pressure–Composition–Temperature experiment), respectively. The structure evolution and phase transition in the Mg-13Y bulk alloy treated at 673 K and at 4 MPa for 40 h were observed by an optical microscopy (OM), a scanning electron microscopy (SEM), a transmission electron microscopy (TEM) and X-ray diffraction (XRD). The large Mg24Y5 phase in the bulk Mg-13Y alloy could be destroyed into fine cuboid-shaped YH2 phases during the hydrogenation process, which is probably responsible for the improvement of mechanical properties of Mg-13Y alloy.

•Structural properties and electronic structure of Al2Zr and Al2Hf are studied.•Mechanical properties are well described and discussed.•The Debye temperature and anisotropic sound velocity are first assessed.•The bonding strength for Al–Zr bonding is stronger than that of Al–Hf bonding.Structural, mechanical and electronic properties of Laves phases Al2Zr and Al2Hf with C14-type structure were investigated by performing the first-principle calculations. The calculated equilibrium structural parameters agree closely with available experimental values. Mechanical parameters, such as bulk modulus B, shear modulus G, Young’s modulus E and the Poisson’s ratio ν are determined within the framework of the Voigt–Reuss–Hill approximation. We show that both Al2Zr and Al2Hf are mechanically stable and brittle with the estimation from the Poisson’s ratio and the B/G relationship. The mechanical anisotropies of the two phases are discussed in detail using several different anisotropic indexes and factors, showing that the anisotropy degree of Al2Hf is slightly larger than that of Al2Zr. In addition, the Debye temperature and anisotropic sound velocity of the two phases are predicted. Finally, the electronic structures are determined to reveal the bonding characteristics of both phases. These results are helpful to deepen the understanding of the physical and chemical nature of C14-type Al2Zr and Al2Hf.

Reducing Mg particles to nanoscale and doping with various catalysts are considered as efficient approaches for improving the hydrogen storage properties of Mg/MgH2. It has been established that doping Ni or Mg2Ni into nano-Mg/MgH2 through physical routes remarkably improves the hydrogen sorption kinetics. In this work, a Mg–Ni nanocomposite has been coprecipitated from a tetrahydrofuran (THF) solution containing anhydrous magnesium chloride (MgCl2), nickel chloride (NiCl2), and lithium naphthalide (LiNp) as the reducing agent. TEM observations reveal that Ni nanoparticles are distributed homogeneously on the surface of those larger Mg particles with sizes ranging from 10 to 20 nm in the nanocomposite. It is observed that γ-MgH2 phase appears when the nanocomposite is hydrogenated at temperatures below 225 °C. Pressure–composition–temperature (PCT) measurements reveal that the Mg–Ni nanocomposite has superior hydrogen storage properties over the pure Mg prepared using the same method. For instance, the Mg–Ni nanocomposite can absorb 85% of its maximum hydrogen capacity within 45 s at 125 °C, and a hydrogen capacity of 5.6 wt % can be obtained within 10 h at room temperature. In addition, the dehydrogenation temperature of the hydrogenated Mg–Ni nanocomposite is also much lower than that of the hydrogenated pure Mg. The hydrogenation and dehydrogenation enthalpies of the Mg–Ni nanocomposite are determined to be −70.0 and 70.7 kJ/mol H2, slightly lower than those for the reduced pure Mg. The excellent hydrogen sorption properties of the Mg–Ni nanocomposite can be attributed to the nanosize effect of Mg particles and the gateway effect of Mg2Ni formed in the composite after hydrogenation/dehydrogenation cycles.

•Mg–TM–La ternary composite powders are prepared directly through arc plasma method.•Both TM and La2O3 improve hydrogen sorption properties of Mg particles.•Mg–TM–La ternary powders show better properties than Mg based binary powders.•Mg–Ni–La powder is able to absorb hydrogen with fairly rapid kinetics at 303 K.For the first time, Mg based Mg–Transition metal (TM) –La (TM = Ti, Fe, Ni) ternary composite powders were prepared directly through arc plasma evaporation of Mg–TM–La precursor mixtures followed by passivation in air. The composition, phase components, microstructure and hydrogen sorption properties of the composite powders were carefully investigated. Composition analyses revealed a reduction in TM and La contents for all powders when compared with the compositions of their precursors. It is observed that the composites are all mainly composed of ultrafine Mg covered by nano La2O3 introduced during passivation. Based on the Pressure–Composition–Temperature measurements, the hydrogenation enthalpies of Mg are determined to be −68.7 kJ/mol H2 for Mg–Ti–La powder, −72.9 kJ/mol H2 for Mg–Fe–La powder and −82.1 kJ/mol H2 for Mg–Ni–La powder. Meantime, the hydrogen absorption kinetics can be significantly improved and the hydrogen desorption temperature can be reduced in the hydrogenated ternary Mg–TM–La composites when compared to those in the binary Mg–TM or Mg–RE composites. This is especially true for the Mg–Ni–La composite powder, which can absorb 1.5 wt% of hydrogen at 303 K after 3.5 h. Such rapid absorption kinetics at low temperatures can be attributed to the catalytic effects from both Mg2Ni and La2O3. The results gathered in this study showed that simultaneous addition of 3d transition metals and 4f rare earth metals to Mg through the arc plasma method can effectively alter both the thermodynamic and kinetic properties of Mg ultrafine powders for hydrogen storage.

Magnesium nanoparticles confined in carbon aerogels were successfully synthesized through hydrogenation of infiltrated dibutyl-magnesium followed by hydrogen desorption at 623 K. The average crystallite size of Mg nanoparticle is calculated to be 19.3 nm based on X-ray diffraction analyses. TEM observations showed that the size of MgH2 particle is mainly distributed in the range from 5.0 to 20.0 nm, with a majority portion smaller than 10.0 nm. The hydrogenation and dehydrogenation enthalpies of the confined Mg are determined to be −65.1 ± 1.56 kJ/mol H2 and 68.8 ± 1.03 kJ/mol H2 by Pressure–composition–temperature tests, respectively, slightly lower than the corresponding enthalpies for pure Mg. In addition, the apparent activation energy for hydrogen absorption is determined to be 29.4 kJ/mol H2, much lower than that of the micro-size Mg particles. These results indicate that the thermodynamic and absorption kinetic properties of confined Mg nanoparticles can be significantly improved due to the ‘nanosize effect’.Highlights► Mg nanoparticles confined within carbon aerogels were successfully prepared. ► Nanoconfined Mg shows superior hydrogen sorption properties over pure Mg. ► ‘Nanosize effect’ plays a key role for the destabilization of nanoconfined MgH2.

Mg based Mg–Rare earth (RE) hydrogen storage nano-composites were prepared through an arc plasma method and their composition, phase components, microstructure and hydrogen sorption properties were carefully investigated. It is shown that the Mg–RE composites have special metal-oxide type core–shell structure, that is, ultrafine Mg(RE) particles are covered by nano-sized MgO and RE2O3. In comparison to pure Mg powders prepared using the same method, the hydrogen absorption kinetics can be significantly improved through minor addition of RE to Mg. In addition, the Mg–RE composite powders show better anti-oxidation ability than pure Mg powders, resulting in the increased hydrogen storage capacity of Mg–RE powders over pure Mg powders. In particular, the hydrogenation enthalpy can be increased and the dehydriding temperature can be reduced through minor addition of Er. The experimental results show that both the RE in solid solution state in Mg and the RE2O3 nano-grains covered on Mg particles contribute to the improved hydrogen storage thermodynamic, kinetic and anti-oxidation properties of Mg ultrafine particles.Highlights► RE (RE = Nd, Gd, Er) doped Mg based composites are prepared by arc plasma method. ► Mg–RE powders are composed of Mg(RE) ultrafine particles covered by MgO/RE2O3. ► Both RE in Mg and RE2O3 on Mg particles improve hydrogen sorption properties. ► Mg–RE composite powers show higher anti-oxidation ability than Mg powders.

Cyclic deformation characteristics of an extruded Mg–10Gd–3Y–0.5Zr (GW103K) magnesium alloy were determined via the strain-controlled low cycle fatigue tests with varying strain ratios at a constant strain amplitude. Unlike the rare-earth (RE)-free extruded magnesium alloys, the present alloy exhibited symmetrical hysteresis loops in tension and compression in the fully reversed strain-control tests at a strain ratio of Rε=−1. This was due to the presence of relatively weak crystallographic textures and the suppression of twinning–detwinning activities arising from the fine grain sizes and RE-rich particles. At a strain ratio of Rε=0 and 0.5, a large amount of plastic deformation occurred in the tensile phase of the first cycle of hysteresis loops due to the high positive mean strain values. With decreasing strain ratio, the hysteresis loops became wider. Fatigue life of this alloy was observed to be the longest in the fully reversed strain control at Rε=−1, and it decreased as the strain ratio was deviated from Rε=−1. A certain degree of mean stress relaxation was also observed in the non-fully reversed strain control (i.e., Rε≠−1 tests).

The application of ultra-lightweight magnesium alloys inevitably involves fatigue resistance under cyclic loading. The present study was aimed at evaluating strain-controlled cyclic deformation behavior and the relevant effect of microstructure in a rare-earth (RE) element containing extruded Mg–10Gd–3Y–0.5Zr (GW103K) alloy. The microstructure of this alloy consisted of fine equiaxed grains with an average grain size of about 12 μm and a large number of RE-containing precipitates. Unlike the RE-free extruded magnesium alloys, this alloy exhibited essentially cyclic stabilization and symmetrical hysteresis loops without tension–compression asymmetry due to the presence of the relatively weaker texture and the suppression of twinning activities arising from the fine grain size and especially RE-containing precipitates. A detailed analysis for understanding the obstructive role of the precipitate to twinning has been presented. While this alloy had a lower cyclic strain hardening exponent than the RE-free extruded magnesium alloys, it had a longer fatigue life which can also be described by the Coffin–Manson law and Basquin's equation. Fatigue crack was observed to initiate from the specimen surface with some cleavage-like facets at the initiation site. Crack propagation was basically characterized by fatigue striations in conjunction with secondary cracks.

Mg containing intermetallic compounds are promising candidates for hydrogen storage. However, the thermodynamic data required to assess the hydriding/dehydriding enthalpies of these compounds are not available yet. In the present work, first principles density functional theory calculations were used to predict the crystal structure, stability, and reaction enthalpies of a LaMgNi4 compound. The cohesive energy (Ecoh) and enthalpies of formation (ΔH) of the corresponding hydrides were calculated. It was found that the structural stability order was γ-LaMgNi4H7 hydride > α-LaMgNi4H hydride > β-LaMgNi4H4 hydride. The reaction enthalpies (ΔHR) for dehydrogenation of the γ-LaMgNi4H7 hydride, α-LaMgNi4H hydride, and β-LaMgNi4H4 hydride were 32.67, 33.08, and 32.05 kJ/mol H2, respectively. The results proved theoretically that LaMgNi4 hydrides had a low dissociation temperature. The electronic structures of the LaMgNi4 compound and its hydrides were also calculated and the results indicated that LaMgNi4 hydrides were promising candidates for reversible hydrogen storage.Highlights► Structure and thermodynamics of LaMgNi4 and its hydrides are theoretically studied. ► Stability of the hydrides has an order of γ-LaMgNi4H7 > α-LaMgNi4H > β-LaMgNi4H4. ► LaMgNi4 is theoretically proved to be a promising hydrogen storage candidate.

A 3NaBH4/YF3 hydrogen storage composite was prepared through ball milling and its hydrogen sorption properties were investigated. It is shown that NaBH4 does not react with YF3 during ball milling. The dehydrogenation of the composite starts at 423 °C, which is about 100 °C lower than the dehydrogenation temperature of pure NaBH4, with a mass loss of 4.12 wt%. Pressure–Composition–Temperature tests reveal that the composite has reversible hydrogen sorption performance in the temperature range from 350 °C to 413 °C and under quite low hydrogenation plateau pressures (<1 MPa). Its maximum hydrogen storage capacity can reach up to 3.52 wt%. The dehydrogenated composite can absorb 3.2 wt% of hydrogen within 5 min at 400 °C. Based on the Pressure–Composition–Temperature analyses, the hydrogenation enthalpy of the composite is determined to be −46.05 kJ/mol H2, while the dehydrogenation enthalpy is 176.76 kJ/mol H2. The mechanism of reversible hydrogen sorption in the composite involves the decomposition and regeneration of NaBH4 through the reaction with YF3. Therefore, the addition of the YF3 to NaBH4 as a reagent forms a reversible hydrogen storage composite.Highlights► 3NaBH4/YF3 system is a found to be a reversible hydrogen storage composite. ► The composite can absorb 3.2 wt% of hydrogen within 5 min at 400 °C. ► NaBH4 can be regenerated at moderate temperatures and low hydrogen pressures.

The effects of pressure on the structural, electronic properties and ionic configuration of MgCu2 Laves phase were investigated by means of the first-principles method based on the density functional theory with generalized gradient approximation. The results for the equilibrium lattice constants are in good agreement with the previous experimental and other theoretical results. The elastic properties including the isotropic bulk modulus B, shear modulus G, Young modulus E and Poisson's ratio ν of the cubic C15-type structure MgCu2 were determined by using the Voigt–Reuss–Hill averaging scheme. The results show that the MgCu2 Laves phase is ductile according to the analysis of G/B and Cauchy pressure. The Debye temperatures obtained from the elastic stiffness constants increase with increasing pressure. Finally, the pressure-dependent behavior of density of states and ionic configuration are successfully calculated and discussed.Highlights► The structural and electronic properties of MgCu2 Laves phase were studied. ► MgCu2 exhibits ductile feature according to the G/B and Cauchy pressure. ► The effects of pressure on elastic modulus and Debye temperatures were studied. ► The effects of pressure on DOS and ionic configuration of MgCu2 were discussed.

Microstructure evolution of Mg–10Gd–3Y–1.2Zn–0.4Zr alloy during high temperature heat-treatment at 773 K in the time range 12–72 h is investigated. Addition of 1.2% Zn increases the amount of Mg5(Gd,Y,Zn) eutectic compounds and form of basal plane stacking faults (SF) of Mg crystal in the as-cast alloy. During heat-treatment at 773 K, parts of eutectic compounds dissolve gradually into the matrix with time prolonged, a new 14H type of LPSO and fcc structured cuboid-shaped RE-rich phases come into being. Two kinds of morphologies of these 14H LPSO phases: block-shaped and fine lamellar-shaped are generated through transformation from Mg5(Gd,Y,Zn) eutectic compounds by heat treatment control.

The effect of parameters such as strain amplitude, frequency and temperature on damping capacity of magnesium alloy AZ91D as-cast, solution and aged was investigated. Granato–Lücke model was employed to explain the influences of parameters on damping capacity of magnesium alloy. It is shown that solution treatment decreases the amount of second-phase particles distributing inside grains, weakens the strong pinning on dislocations, and increases the internal friction of AZ91D, while aging reduces the value due to precipitation of second-phase particles. The influence of solution treatment and aging on damping capacity of AZ91D at room temperature is the same as at 100 °C. The damping at 100 °C is greater than that at room temperature because of thermal activation.