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The present study investigated the effect of Gd on the microstructures and mechanical properties of permanent mould cast Mg-4Al-5RE (wt%) (where RE represents La-Ce mischmetal) alloy. Coarse grains and acicular Al11RE3 phases in Mg-4Al-5RE alloy are successfully refined by the addition of 0.66 wt% Gd. The average grain size is dramatically decreased from 493.9 μm to 205.8 μm, and the acicular Al11RE3 phase is modified to rod-like sharp with a pronouncedly decreased average length from 22.0 μm to 3.8 μm. The modified microstructures are attributed to the formation of Al2(Gd, RE) particles, which act as nucleation sites for both α-Mg and Al11RE3. Eventually, the modified alloy exhibits dramatically enhanced yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) about 12%, 23% and 48%, respectively.

A Ca-containing Mg-4Zn-1MM(mischmetal)-0.1Ca (wt.%, ZEX4101) alloy sheet shows Index Erichsen value of 6.7 mm, which is better than commercial Mg alloy sheets. The good formability is attributed to its weakened basal texture, in which the intensity of the (0001) poles of the recrystallized grains spreads towards the transverse direction. By monitoring the microstructural evolution during the hot rolling and the solution treatment, we found that Ca addition hinders the formation of strong basal texture during the rolling. During the subsequent solution treatment, static recrystallization mainly proceeds by the growth of dynamically recrystallized grains, and then the weak texture feature of the dynamically recrystallized grains is maintained in the ZEX4101 alloy sheet. It is hypothesized that co-segregation of Zn and Ca atoms to the grain boundaries prevents the rotation of the (0001) poles of the dynamically recrystallized grains toward the sheet normal direction, resulting in the development of weak basal texture in the ZEX4101 alloy sheet.

The relative potential difference can be treated as an index of local corrosion of alloys. Since local corrosion is driven by the micro-galvanic coupling, which is consist of the micro-constituent phases and the matrix. They present distinct potential difference normally. In the present work, the relationship between the Volta potential and the corrosion effect of the dominated intermetallic phase in the AZ91 Mg alloy with (La, Ce) MM addition was investigated. A multiscale approach coupling global and local measurements was used to study the corrosion behavior of the alloy and its intermetallic phase. Results showed that the microstructure of AZ91 Mg alloy with (La, Ce) MM addition was complex, with the presence of Al4(La, Ce) phases in acicular or rod shape, a small number of Al8Mn4Ce, β-Mg17Al12 and α-Mg solid solution. In this case, the improved corrosion resistance of the alloy was achieved. Scanning Kelvin probe force microscopy (SKPFM) analysis revealed that all the intermetallics were noble comparing with the α-Mg solid solution. In-situ electrochemical atomic force microscopy (EC-AFM) observation for the initial stages of corrosion showed the α-Mg matrix surrounded by β-Mg17Al12 or Al8Mn4Ce was susceptible to pitting corrosion. No noticeable corrosion occurred at the α-Mg adjacent to Al4(La,Ce) phase, in spite of the relatively higher difference of Volta potential between Al4(La,Ce) phase and the matrix. Volta potential is insufficient to determine whether the phase is an effective cathode or anode.

LaNi5-type alloys are commercial materials for the negative electrode in Ni-MH rechargeable batteries. Partial substitution of La by mischmetal (Mm) and of Ni by elements like Co, Al, and Mn significantly improve the cycle stability and high-rate discharge capacity of the electrodes. The partial substitution of Ni by Cu was studied previously for several selected ternary alloys with a special focus on crystal structure change upon substitution and gas phase hydrogen absorption. We present in this paper the results of the study of the electrochemical activation, discharge kinetics, equilibrium charge/discharge, and cycle life of electrodes made from four different LaNi5-xCux (x = 0.1, 0.5, 0.9, 1) alloys in order to provide full insights into utilization of these alloys.

This study investigated the high-temperature mechanical properties and collaborative working mechanism of zinc-5% aluminum-mixed mischmetal alloy-coated steel strand cables (M-C cables) and internal steel wires by numerical analysis, based on the experimental data for the high-temperature mechanical properties of steel wire. The high-temperature mechanical properties of zinc-5% aluminum-mixed mischmetal alloy-coated steel (M-C steel) with round and Z-shape cross-section shapes were studied in the temperature range of 30–800 °C using the constant temperature loading test method. The two-stage Ramberg-Osgood model for M-C steel wires at elevated temperatures is proposed for modeling of the M-C steel wires. Furthermore, the equations for the reduction in the nominal yield strength, elastic modulus and ultimate strength for M-C steel wires at elevated temperatures are proposed. Numerical analysis and investigation of the high-temperature mechanical properties of normal M-C cables and locked M-C cables under eight temperature conditions are carried out. Based on the high-temperature constitutive relationship of the round and Z-shaped M-C steel wires obtained experimentally, the thermostatic drawing process is simulated at different temperatures for two types of M-C cables. The high-temperature stress-strain relationship between the two and the relevant high-temperature mechanical performance index were obtained. According to the numerical simulation results, the energy, contact stress distribution and radial displacement deformation of M-C cables under the different temperature condition were evaluated and analyzed. The collaborative working mechanism of M-C cabled affected by temperature was revealed.

Magnesium alloys are important alternatives for structural weight reduction due to their low density and good specific mechanical strength. Among the magnesium alloys, the ZK type exhibits the highest mechanical strength. However, it has limitations on hot working or welding owing to the presence of intermetallics with low melting point and consequently susceptibility to hot crack formation. The addition of rare earths tends to form intermetallics with higher melting points, thus inhibiting the formation of hot cracks, as well as building up thin and dense surface films that improve corrosion resistance. This work studies the addition of 1.5% wt. of mischmetal (Mm) to the ZK60 alloy, and then demonstrates the effects of the casting process with mechanical mixing in the semi-solid state. The alloys produced were: ZK60 and ZK60–1.5 wt%Mm manufactured by conventional casting and rheocast ZK60–1.5 wt%Mm produced with mechanical mixing in the semi-solid state. The casting and cooling methods result in defect-free and chemically homogeneous materials, and the mechanical mixing provides a homogeneous microstructure with globular grains. The mechanical strength was though higher for the ZK60 alloy due to its increased solute content within the Mg-matrix and the smaller quantity of intermetallics that builds up an intermittent network. The Mg7Zn3 intermetallic, which is the main precipitate for ZK60 alloy, has hardness 20% higher than the MgZn2Ce intermetallic that is precipitated with the mischmetal addition and partly removes solute from the Mg-solid solution.

Coercivity enhancement of hot-deformed NdFeB magnets made from commercially available NdFeB powders doped with Ce-containing alloys is demonstrated. By doping (Pr71Nd27Ce2)70Cu30 powders, where Pr71Nd27Ce2 is a commercial mischmetal, the hot-deformed magnets exhibit significant enhancement of coercivity from 15.0 kOe to 19.0 kOe, and it can reach 20.1 kOe by doping higher Ce-content (Pr71Nd9Ce20)70Cu30 powders, yet sustains high energy product. The magnetic isolation effect with Ce-containing phase in the grain boundary and the microstructure refinement lead to coercivity enhancement. This study provides an economic way to enhance coercivity of hot deformed NdFeB magnets without using heavy rare earth.

This work presents results on the effect of mischmetal (MM) content on the magnetic properties, phase formation, microstructure, and intergranular interactions in MM12+xFe78-xCo2B6 (x = 0, 4, 8) magnets. The MM-FeCo-B magnets have been prepared by Spark Plasma Sintering method from powders obtained by grinding precursor nanocrystalline ribbons. A significant increase in coercivity of almost 50%, from 5.4 kOe to 10.2 kOe, has been obtained when the MM content increased from 12 at% to 20 at%, while the remanence decreased with about 30%, from 100.3 to 74.45 emu/g. X-ray diffractograms analysis indicates that for a MM content higher than 12%, in addition to the 2: 14: 1 main phase, secondary phases are formed, the amount of which increases when the MM content increases. Electron microscopy investigations have shown that the secondary phases accumulate at the boundaries of the main phase grains. In the case of the magnet with 20 at% MM content the main phase grains are completely isolated. As a result, the magnets show a weakening of the exchange interaction, explaining thus the increase in coercivity. The best magnetic properties, such as coercivity of about 8.7 kOe and maximum energy product of 11.19 MGOe, have been obtained for the magnet with 16% MM content, which is promising for practical applications in terms of filling the gap between ferrites and Nd-Fe-B magnets.

The influence of mischmetal (lanthanum and cerium) on the microstructure and mechanical properties of Mg-9Li-3Al-xRE (x=0, 0.5, 1, 1.5, 2, wt%) alloys was investigated by optical microscope, scanning electron microscope (SEM) with an energy dispersive spectroscope (EDS), and X-ray diffraction (XRD). In as-cast alloys, Al4RE phase is formed, the content of Mg17Al12 phase and the volume fraction of α-Mg phase decrease. In addition, α-Mg phase is refined and the mechanical properties of Mg-9Li-3Al-xRE alloys are improved. However, with increasing mischmetal content, the size of Al4RE phase increases and the mechanical properties decrease. In extruded alloys, Al4RE phase is broken into the particles of 1∼3 μm in the β-Li matrix phase and α/β interphase. And the best mechanical properties are obtained for Mg-9Li-3Al-1.5RE alloy with a tensile strength of 228.3MPa and elongation of 20.8%, increased by 88.6% and 197.4%, respectively, compared with as-cast Mg-9Li-3Al alloy.

Magnetic materials of MM-Fe-B (MM=mischmetal) ribbons were prepared using melt spinning method by varying the content of MM. The ribbons contain minor phases besides the main phase of Re 2 Fe 14 B. X-ray techniques show that the diffraction peak intensities of the minor phase Fe 3 B vary with the content of constituent elements, indicating that the amount of minor phase could be tunable. The squareness of hysteresis loop is the best in MM 13 Fe 80.5 B 6.5 ribbons, which should mainly ascribe to the less amount of minor phase. Henkel plots verify the more uniform magnetization reversals in MM 13 Fe 80.5 B 6.5 ribbons, and the energy product achieves to the maximum of 12.74 MGOe with the coercivity of 6.50 kOe. With the increase of MM content the coercivity increases monotonically, and reaches to 9.13 kOe in MM 15 Fe 77.5 B 7.5 ribbons, which should be related with the nature of the defects in the main phase. These investigations show that optimizing the content of constituent elements and phase constitution could improve magnetic properties in the resource-saving magnets of MM-Fe-B ribbons.

Mischmetal-Fe-B ribbons were prepared by melt-spinning method, and industrial mischetal with low purity was selected as the raw material. By introducing La and employing nonequilibrium technology, we successfully avoid the formation of CeFe 2 phase, which decreases magnetic performance greatly. Considerable energy product and intrinsic coercivity were achieved in (MM) 2.4 Fe 14 B, which are 80.69 kJ/m 3 and 500 kA/m, respectively. Phase composition and magnetization process of all the samples were investigated. Strong pinning effect was found in all rare-earth-rich samples and was identified as a crucial factor to obtain high coercivity in ribbons compared with the sintered magnets. The Henkel plot is also measured to investigate the intergrain interaction and the results show a strong exchange coupling between grains. Based on these results, the difference in magnetic performance between nanocrystalline ribbons and sintered magnets can be explained.

Aluminium and magnesium are known for their ability to improve corrosion performance of zinc coatings used for steel protection in automotive applications. To investigate the inhibiting properties of other elements, series of model Zn X, Zn Al X, Zn Mg X and Zn Al Mg X alloys containing 0.2–2 wt% of titanium, mischmetal (mixture of cerium and other lanthanides), zirconium, molybdenum, chromium, boron, gallium, indium, copper, nickel, calcium, manganese and silicon were prepared and their corrosion performance in a cyclic accelerated test and at a marine field site and the ability to provide galvanic protection to steel in defects were characterized. On openly exposed surfaces, none of the investigated elements showed stronger inhibiting effect on atmospheric corrosion than Al and Mg. When exposed to marine climate, it was beneficial to combine Al and Mg. The corrosion stability of Zn Al Mg was further improved by addition of a fourth element. Quaternary Zn Al Mg X alloys outperformed binary Zn X and ternary Zn Al X and Zn Mg X alloys. In average, mass loss was 4-fold higher in confined zones simulating hem flanges. Strong inhibition with Mg and detrimental effects of Al on corrosion in confined zones was found. Several quaternary Zn Al Mg X alloys with improved corrosion stability in both open and confined configurations were identified.

Effects of the mischmetal addition in range of 0.4 wt.% to 1.7 wt.% on the microstructure and mechanical properties of die-cast magnesium AZ91D were investigated to improve the elevated temperature mechanical properties of the alloy by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and tensile tests. The results revealed that mechanical properties of die-cast magnesium alloy AZ91D-0.4%MM at 100 °C were near to those of die-cast magnesium alloy AZ91D. The ultimate tensile strength, 0.2% proof yield strength and elongation to failure of die-cast magnesium alloy AZ91D at 170 °C were 178, 129 MPa and 20%, respectively. In comparison, the ultimate tensile strength, 0.2% proof yield strength and elongation to failure of die-cast magnesium alloy AZ91D-0.4%MM at 170 °C reached to 206, 142 MPa and 26%, respectively increased by 15.7%, 10% and 30%. Proper addition of mischmetal could enhance the mechanical properties at an elevated temperature, which was attributed to the formation of Al-RE phases with high thermal stability. Hence sliding of grain boundaries and cracks could be effectively hindered by Al-RE phases.

The microstructure and mechanical properties investigations of two AME503 and AME505 experimental alloys in as-cast conditions were presented. The investigated materials were fabricated on the basis of the AM50 commercial magnesium alloy with 3 and 5 wt.% cerium rich mischmetal. In the as-cast condition, both experimental alloys were mainly composed of α-Mg, Al11RE3 and Al10RE2Mn7 intermetallic phases. Additionally, due to non-equilibrium solidification conditions, a small amount of α + γ divorced eutectic and Al2RE intermetallic phase were revealed. The obtained results also show a significant influence of rare earth elements on Brinell hardness, tensile and compression properties at ambient temperature and especially on creep properties at 473 K. Improved alloy properties with a rise in rare earth elements mass fraction results from an increase in Al11RE3 phase volume fraction and suppression of α + γ eutectic volume fraction in the alloy microstructure. Additionally, the influence of rare earth elements on the dendrite arm space value was discussed. The presented results also proved the thermal stability of the intermetallic phases during creep testing.

Two duplex Mg–Li alloys, Mg–8.02Li–0.210Y and Mg–8.43Li–0.353Ymm (Y-rich mischmetal) alloys, were prepared by casting method with a permanent metal model. Microstructures, mechanical properties and deformation behaviors at tensile rates from 1.28 × 10−4 s−1 to 1.28 × 10−3 s−1 were evaluated. The results showed that when increasing the tensile speed, the strength increased with a decreasing elongation. The strength and ductility of Mg–8.02Li–0.210Y alloy were more sensitive to the tensile speed. Fracture occurred mainly in the β-Li phase, and the α-Mg phase participated into fracture at relatively high tensile speeds, which led to the strength increase of both alloys with the increment of tensile speed. Long-stripe-like α-Mg grains in Mg–8.02Li–0.210Y alloy hindered the fracture and resulted in a higher elongation. Mg–8.02Li–0.210Y alloy presented a serrated effect at a relatively high initial rate of 1.28 × 10−3 s−1. This was proposed to be resulted from the interaction between slips and α-Mg grains, which was quite different from the serrated effect explained by the dynamic strain aging (DSA) mechanism. Keywords: Mg–Li alloy, Dual phase, Tensile speed, Serrated effect, Slip

Multiwalled carbon nanotubes have interesting electrochemical properties that can be utilized for the energy storage application. However, the practical application of multiwalled carbon nanotubes is limited by the current techniques to provide large scale production. So, the large scale production of multiwalled carbon nanotubes is obtained by catalytic chemical vapor deposition of acetylene/liquified petroleum gas on diatom supported Mischmetal based nickel alloy catalyst. The developed multiwalled carbon nanotubes are uniform in diameter and the method of production does not require any process of purification. The multiwalled carbon nanotubes along with the presence of diatom is used as the high capacity anode for the lithium-ion battery. The interaction of lithium ions with both multiwalled carbon nanotubes and diatom increases the specific capacity to 1090 mAh g−1 at 0.05 A g−1 with cyclic durability of 2000 cycles. This work demonstrates a scalable method for the production of multiwalled carbon nanotubes from a cost-effective catalyst with the benefit of utilizing it as a high capacity anode material for lithium-ion battery.

In this study, the wear and corrosion characteristics of six-pass friction stir processed (FSPed) AA1050/mischmetal oxide nanocomposite (6PPA) was compared to six-pass FSPed sample without powder (6 PA) and annealed base metal (BM). Different wear characteristics, such as weight loss, wear rate and coefficient of friction (COF) were studied. In order to evaluate the corrosion resistance of samples, immersion and cyclic polarization tests were performed. In addition, worn and corroded surfaces were investigated by field emission scanning electron microscopy (FESEM). The result of pin on disk dry sliding wear test revealed that wear resistance improved by employing FSP through finer grain structure (6 PA sample) and by incorporation of mischmetal oxides (MMOs) through lubrication and load-bearing action of particles (6PPA sample). At the constant load of 30 N, COF decreased from 0.9 to 0.85 and 0.75, and weight loss from 7.4 to 5.7 and 4.5 mg/m × 10−3 for the BM, 6 PA, and 6PPA samples, respectively. According to FESEM study of the worn surfaces, the BM and 6 PA samples show an adhesive wear mechanism, however the wear mechanism changed to abrasive for 6PPA sample. Based on immersion test results, corrosion rate of BM reduced from 0.41 to 0.36 and 0.29 mpy for the 6 PA and 6PPA samples, respectively. Moreover, the results of cyclic polarization test and FESEM investigation showed improved pitting resistance of 6PPA sample.

In order to prepare high-performance low-cost sintered (Nd, MM)-Fe-B magnets, the effect of the microstructure of strip-casting alloys on the particle size and distribution of powder was first investigated in this work. By adding lubricant and antioxidant to improve orientation and control oxygen content, the mischmetal-based sintered magnet possessing fine grains (~2.5 μm) along with smooth and continuous grain boundaries could maintain the excellent magnetic properties of Br = 12.31 kG, Hcj = 9.61 kOe and (BH)max = 36.52 MGOe by optimizing two-stage annealing temperature. The magnet prepared in this work exhibits record-high magnetic properties in the same proportion of MM substitution, which provides useful guidance for the preparation of MM doped magnets.

Surface hybrid in-situ aluminum matrix nanocomposite (AMNC) was fabricated by multi-pass friction stir processing (FSP) and a tool traversing speed of 100 mm/min and rotating speed of 1600 rpm with an objective to enhance mechanical properties. Mischmetal oxide (MMO) powder with an initial size of 50 nm, at a concentration of 8.5 vol% was used as the reinforcing particles. EDS particle analyses revealed in-situ solid-state chemical reactions between the Al matrix and the MMO particles. The reaction products, MM3Al and MM3Al11, were distributed uniformly in the discontinuously dynamic recrystallized nano and UFG microstructure. Increasing pass number improved the particle distribution and decreased agglomerated particle size while promoting the in-situ solid-state reaction. The nanocomposite produced by 6 FSP passes enhanced yield stress, 180% (YS = 70 MPa) and strength, 120% (UTS = 132 MPa) while reduced the tensile ductility from 35% to 23%. Fractographic studies showed that dimple-shape ductile fracture mode changed to ductile-brittle mode.

One of the prominent applications of magnesium alloys, thoroughly investigated in recent years, is medicine. The commercial WE43 (Mg-4wt.%Y-3wt.%mischmetal) alloy was reported to exhibit superior in vitro and in vivo performance, however, the presence and possible harmful effect of rare earth (RE) elements mischmetal in this alloy have been vastly debated. For this reason, the RE mischmetal was substituted in this study by pure neodymium, which exhibits rather low toxicity. In this way, a novel WN43 (Mg-4wt.%Y-3wt.%Nd) alloy was prepared, with well-defined composition. In order to attain a good control over the grain size and phase distribution, a modern spark plasma sintering (SPS) method was employed. The main objective of this study was to examine the effect of sintering parameters on the resulting microstructure (type and morphology of secondary phases, grain structure, and residual strain) and microhardness (Hv). The application of relatively high pressure (100 MPa) during consolidation leads to the production of practically fully compact final material. Increasing sintering temperature (from 400 up to 500 °C) stimulated homogenization and stabilization of the microstructure and reduction of the internal strain. On the other hand, the effect of sintering time (3 or 10 min) was rather negligible. Furthermore, the microhardness experiments revealed that the softening effect due to homogenization and decrease in the dislocation density at higher sintering temperatures was well-compensated by precipitation hardening as the hardness values were comparable in all the samples. The understanding of microstructure evolution as a function of sintering parameters can be of particular importance for subsequent mechanical, corrosion and in vivo degradation testing of this novel biomedical magnesium alloy.

This study investigated the mechanical properties of zinc-5% aluminum-mixed mischmetal alloy-coated steel strand cables (M-C cables) with diameters ranging from 12 mm to 22 mm. A total of 24 tensile tests were conducted to obtain the nominal yield strength, ultimate strength, elastic modulus, fracture strain, and stress-strain curves for M-C cables with varying diameters. The stress-strain curves of the test specimens were fitted using the modified Ramberg and Osgood models to obtain stress-strain models for M-C cables with different diameters. Based on the actual boundary of the cable used in engineering practice, a new finite element model was established with ABAQUS finite element analysis software. Based on the finite element model, the development of the stress in each layer of steel wire, change in the contact pressures between the wires, and the friction energy dissipation between the wires were analyzed with continuous elongation of the cable.

The microstructure and mechanical properties of Mg–Zn-0.5Ca-0.5RE magnesium alloy, with zinc contents of 0, 2, 4, and 6 wt%, were studied. A significant effect of Ca and rare earth (RE) elements (via mischmetal addition) on the grain refinement of cast ingots was observed with the consequent enhancement of ultimate tensile strength (UTS). Moreover, while the grain size was refined by the addition of Zn, no significant α-Mg grain refinement occurred beyond 2 wt% Zn addition. The Mg12RE intermetallic compound was observed in all alloys while the Mg7Zn3 phase formed at the grain boundaries of Zn-containing alloys. Based on the competition of grain refinement as a favorable factor and formation of unfavorable grain boundary phases, the Mg–4Zn-0.5RE-0.5Ca (ZEX400) alloy showed the highest UTS among the cast alloys. Intense grain refinement introduced by the extrusion process and the fracturing and dispersion of the grain-boundary phases resulted in the significant enhancement of strength and ductility and the appearance of ductile fracture surface for the extruded Mg–4Zn-0.5RE-0.5Ca alloy. It was found that high Zn content (∼6 wt%) limits the usability and hot working temperature range of the alloys due to the problem of hot shortness and intergranular brittle fracture. Therefore, the addition of 4 wt% Zn was recommended for industrial practice. This work revealed the significant effects of alloying (with Ca, RE, and Zn) and hot extrusion process for microstructural refinement and enhancement of mechanical properties of Mg alloys.

Compositions of low–cost (La,Ce,Pr)(Ni,Mn,Al) 5 alloys having hydrogen storage properties comparable to those of (La,Ce,Nd,Pr)(Ni,Co,Mn,Al) 5 commercial alloy were suggested. The compositions were obtained by simultaneously increasing the proportions of Ce, Ni, and Mn and reducing the proportions of Nd and Co. The compositions of the low–cost alloy were proven to be useful through estimation of the hydrogen storage capacity, plateau pressure, and cycling property. It was found that the hydrogen storage capacity and plateau pressure of the low–cost (La,Ce,Pr)(Ni,Mn,Al) 5 alloys are similar to those of the (La,Ce,Nd,Pr)(Ni,Co,Mn,Al) 5 commercial alloy. The hydrogen storage capacity of the low–cost alloy was observed to degrade slightly (about 9%) after 1000 iterations of cycling due to the protective effect of mischmetal and Al, even though the low–cost alloy does not contain Nd and Al in proportions different from those of the commercial alloy.

Rare-earth (RE) mischmetal modification, homogenous annealing and rolling techniques were used to improve the microstructure and mechanical properties of an Al−1Fe alloy. Al 3 Fe, Al 6 Fe and Al 3 Ce intermetallic phases were found in the RE-modified alloys in the as-cast state. The RE modification refined the α-Al grains, resulting in a divorced eutectic and the formation of the Al−Fe phases in the forms of discontinuous networks, flakes and particles. Elemental La dissolved in the Al−Ce phases but did not dissolve in the Al−Fe phases. The dissolution of elemental Ce in the Al−Fe phase along with homogeneous annealing caused the claw-like Al−Fe phases to transform into short flakes and particles, which were uniformly distributed in the matrix by the rolling processes. A 0.3 wt% RE modification had the optimized effect on the microstructure and mechanical properties, while a 0.4 wt% RE addition resulted in the aggregation of the Al−Ce particles, which then deteriorated the mechanical properties of the alloys.

In the present work, the influence of the additions of zinc, zirconium and cerium-rich mischmetal on the microstructural recrystallization development of magnesium were investigated. Grain size and chemical composition were the principal variables of the billets used for indirect extrusion experiments. Significant changes in the evolution of the dynamic recrystallization (DRX) process as a function of the alloying element contents and the process variables were observed. Microstructures and preferred orientation of crystallites were correlated in order to discuss the role of alloy composition on the DRX. This discussion was based on the macro-texture measurements and some EBSD measurements of selected samples.

In the present work, fcc-Al nanoparticle development in Al 90− x Ni 10 MM x (MM: Ce mischmetal; x =2, 4) amorphous alloys was studied via non-isothermal differential scanning calorimetry, X-ray diffraction, transmission electron microscopy, and nanoindentation test. Results showed that the crystallization of Al 88 Ni 10 MM 2 alloy occurred by the precipitation of fcc-Al nanoparticles followed by the crystallization of Al 11 MM 3 and Al 3 Ni phases. Transmission electron microscopy revealed that the aluminum precipitates had an average size of ~12 nm with a round morphology. Increasing the mischmetal content to 4 at% (Al 86 Ni 10 MM 4 alloy) caused a three-stage crystallization process with a change in the size and morphology of fcc-Al precipitates. Here, fcc-Al nanoparticles got an irregular and cluster-like morphology with an average size of about 50 nm. The crystallization mechanism of fcc-Al nanoparticles formation was evaluated. The results indicated the complex nature of the primary crystallization behavior of these amorphous alloys. Results of nanoindentation test revealed that controlled crystallization of the amorphous alloys significantly increased the strength, owing to the solute enrichment of the amorphous matrix.

Al86Ni10MM4 (MM: Mischmetal) amorphous ribbons were prepared by melt spinning on a child copper wheel. Non-isothermal crystallization kinetics of the amorphous alloy was studied by differential scanning calorimetry (DSC). The crystallized phases were determined by X-ray diffraction method and transmission electron microscopy. DSC traces were analyzed by Kissinger method to determine the apparent activation energy of crystallization. Changes in the activation energy (Eα) with progression of crystallization were also evaluated by differential iso-conversional method of Friedman. For the precipitation of nanometer-sized Al particles, the activation energy slightly increased with increasing the conversion fraction up to α = 0.2, but remained almost constant until α = 0.8. Because of the solute enrichment around the particles in the matrix, higher values of Eα were obtained at the late stage of crystallization. Results of nano-indentation test also showed a significant improvement in the hardness of the ribbons due to the formation of fcc-Al nanoparticles.

The as-sintered sinter skin of WC—11Co—0.71Cr3C2—0.06RE cemented carbide with WC+β microstructure was analyzed by scanning electron microscope, energy dispersive X-ray spectroscope and X-ray diffractometer. RE represents La-, Ce-, Pr- and Nd-containing mischmetal, and β is cobalt-based binder phase. It was discovered that La, Ce, Pr and Nd migrated directionally from the alloy to the sinter skin to combine with the impurity elements S and O from the sintering atmosphere during the sintering process. As a result, main dispersed phase RE2S3 and minor RE2O2S were formed in situ on the sinter skin. The mechanisms for the stimulation of the migration activity and the directional migration of RE atoms were discussed in terms of the thermodynamics stability of Cr3C2, solubility characteristic of Cr in Co and the polarization or ionization of RE atoms.

The influence of various fillers R (R = Sr, La, Mm, DD, SrMm, SrDD with Mm standing for mischmetal and DD for didymium) on the physical properties of the triple- and multifilled n-type skutterudites with the nominal composition (R 0.33 Ba 0.33 Yb 0.33 ) 0.35 Co 4 Sb 12.3 is investigated. In comparison to values from previous works of the authors and from the literature it is demonstrated that even small changes in the filling fractions of the fillers as well as in the total filling level influence the power factor and the thermal conductivity. These skutterudites, partially filled with multiple fillers of different chemical nature, can achieve high power factors (>6 mW m −1 K −2 at 823 K) and at the same time low thermal conductivity, resulting in ZT = 1.4 at 823 K. On the contrary, Yb 2 O 3 as a secondary phase in (Sr 0.25 Ba 0.25 Yb 0.50 ) 0.5 Co 4 Sb 12.5 significantly reduces the thermoelectric (TE) performance due to a decreased power factor and an increased lattice thermal conductivity. However, a homogeneous nanoscale distribution of these impurities substantially improves the TE performance, resulting in ZT values of ∼1.6 at 835 K. The ZT value of this skutterudite could be further enhanced to 1.9 (at 835 K) after severe plastic deformation via high-pressure torsion.

Totalized Hydrogen Energy Utilization System (THEUS), which consists of fuel cells, water electrolyzers, hydrogen storage and their auxiliary components, is proposed for the stationary application. In the previous researches, mischmetal-based MmNi 5 compound was used for the stationary hydrogen storage in THEUS. However, the cost of mischmetal is so expensive that can be an obstacle to the practical use of THEUS. In addition, since THEUS utilizes hydrogen produced by water electrolysis, it is necessary to confirm the influence of the water contamination on the metal hydride reactivity. The samples were Ti 0.24 Zr 0.76 Ni 1.2 Mn 0.64 V 0.14 Fe 0.18 (Sample A) and the sample with 1 at.%-La addition (Sample B). Using hydrogen including 40 ppm-water, hydrogen absorption and desorption was carried out 30 times. The degradation of hydrogen storage capacity was observed for Sample A while not observed for La-added Sample B. The results revealed that the addition of La improved cyclic stability against the water contamination.

Hydrothermal crystallization was conducted to improve the diffusion barrier performance of Zr thin films to prevent a fuel clad chemical interaction (FCCI) at the interface between a clad material and lanthanide elements (Mischmetal: 75Ce–25La; intermetallic compound) as fission product. The crystalline phase and size of Zr thin films deposited on a HT9 disk by RF magnetron sputtering were varied by hydrothermal crystallization in an autoclave at 393 K, 423 K and 453 K. Diffusion couple tests of the clad with and without a Zr diffusion barrier were performed at 933 K for 25 h with mischmetal, which have diffusion properties similar to uranium metal composite fuel. While substantial FCCI occurred at the interface between the mischmetal and clad in the specimen without hydrothermal crystallization, the Zr barrier with hydrothermal crystallization showed excellent resistance to FCCI. The performance of the Zr FCCI barrier was improved due to a decrease in interdiffusion by the grain boundary, which can increase the FCCI in the Zr barrier.

Eighteen as-cast binary Mg–Ni, Mg–Mm and ternary Mg–Ni–Mm and Mg–Ni–TM (TM=transition metals (Cu, Zn, Mn and Co); Mm = mischmetal containing Ce, La, Nd and Pr) alloys were hydrided by an electrochemical process to determine the alloys with the most potential for electrochemical hydrogen storage. The alloys were hydrided in a 6 mol/L KOH solution at 80 °C for 480 min and at 100 A/m 2 . To assess the electrochemical hydriding performance of alloys, maximum hydrogen concentrations, hydrogen penetration depths and total mass of absorbed hydrogen in the alloys were measured by glow discharge spectrometry. In addition, the structures and phase compositions of the alloys both before and after hydriding were studied by optical and scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction. It was determined that the highest total amount of hydrogen was absorbed by the Mg–25Ni–12Mm and Mg–26Ni (mass fraction, %) alloys. The maximum hydrogen concentrations in the Mg–25Ni–12Mm and Mg–26Ni alloys were 1.0% and 1.6%, respectively. The main hydriding product was the binary MgH 2 hydride, and the ternary Mg 2 NiH 4 hydride was also detected in the Mg–25Ni–12Mm alloy. The electrochemical hydriding parameters achieved are discussed in relation to the structures of alloys, alloying elements and hydriding mechanisms.

The substitution of Y by mischmetal was investigated on the Mg 65 Cu 25 Y 10 metallic glass, in order to reduce pure rare earth content and improve manufacturing for potential applications. Works showed that this substitution is well accommodated by partial substitution of Cu by Ni. Alloys were prepared by planar flow melt spinning, with various amounts of mischmetal (0, 5 or 10 at.%) and Ni (0, 5, 12.5, 20 or 25 at.%). With increasing content of mischmetal and nickel, the glass forming ability, especially the width of the supercooled liquid region tends to decrease. However, an optimal substitution of Cu by Ni (12.5 at.%) in an alloy free from Y has been identified to present an appreciable glass forming ability with a supercooled liquid region of 35 K.

The influence of mischmetal (Ce-La) addition on phase transformation and as-cast microstructure characteristics of M2 high-speed steel (HSS) was investigated using Thermo-Calc software, differential scanning calorimetry, X-ray diffractometry and scanning electron microscopy with energy dispersive spectrometry. The results showed that the measured phase transition points of M2 HSS were broadly consistent with the theoretical results. After mischmetal addition, the liquidus peak temperature, the peak temperature of the eutectic precipitation of M 6 C and MC were all increased, especially for the M 6 C which was affected significantly and increased about 31 °C. The contents of Mo and V in the eutectic carbide decreased and that of Fe increased, while in the matrix, the Mo, V and Cr contents all increased slightly. Furthermore, the microstructure of as-cast dendrite and ledeburite were refined, the total eutectic carbide content decreased and distributed into a discontinuous network, the lamellar spacing of M 2 C was reduced and the lamellae became thinner.

This paper reports the catalytic effects of mischmetal (Mm) and mischmetal oxide (Mm-oxide) on improving the dehydrogenation and rehydrogenation behaviour of magnesium hydride (MgH 2 ). It has been found that 5 wt.% is the optimum catalyst (Mm/Mm-oxide) concentration for MgH 2 . The Mm and Mm-oxide catalyzed MgH 2 exhibits hydrogen desorption at significantly lower temperature and also fast rehydrogenation kinetics compared to ball-milled MgH 2 under identical conditions of temperature and pressure. The onset desorption temperature for MgH 2 catalyzed with Mm and Mm-oxide are 323 °C and 305 °C, respectively. Whereas the onset desorption temperature for the ball-milled MgH 2 is 381 °C. Thus, there is a lowering of onset desorption temperature by 58 °C for Mm and by 76 °C for Mm-oxide. The dehydrogenation activation energy of Mm-oxide catalyzed MgH 2 is 66 kJ/mol. It is 35 kJ/mol lower than ball-milled MgH 2 . Additionally, the Mm-oxide catalyzed dehydrogenated Mg exhibits faster rehydrogenation kinetics. It has been noticed that in the first 10 min, the Mm-oxide catalyzed Mg (dehydrogenated MgH 2 ) has absorbed up to 4.75 wt.% H 2 at 315 °C under 15 atmosphere hydrogen pressure. The activation energy determined for the rehydrogenation of Mm-oxide catalyzed Mg is ∼62 kJ/mol, whereas that for the ball-milled Mg alone is ∼91 kJ/mol. Thus, there is a decrease in absorption activation energy by ∼29 kJ/mol for the Mm-oxide catalyzed Mg. In addition, Mm-oxide is the native mixture of CeO 2 and La 2 O 3 which makes the duo a better catalyst than CeO 2 , which is known to be an effective catalyst for MgH 2 . This takes place due to the synergistic effect of CeO 2 and La 2 O 3 . It can thus be said that Mm-oxide is an effective catalyst for improving the hydrogen sorption behaviour of MgH 2 .

In this work, the electrochemical hydriding method was used for storing hydrogen in four binary Mg–Ni (Ni content from 15 to 34 wt.%) alloys and one ternary Mg–26Ni–12Mm alloy. Both the as-cast and powdered alloys were hydrided in a 6 M KOH solution at 80 °C for 120–480 min. The structures and phase compositions of the alloys, both before and after hydriding, were studied using optical and scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction. Differential scanning calorimetry and mass spectrometry were used to study the dehydriding process. In the case of as-cast alloys, the best combination of hydriding parameters (maximum hydrogen concentration on surface; depth of hydrogen penetration) was achieved in the Mg–26Ni alloy. In the case of powdered alloys, the Mg–34Ni alloy absorbed the highest amount of hydrogen, nearly 4.5 wt.%. The only hydride formed during hydriding was the MgH 2 hydride. The results of the mass spectrometry analysis reveal a significant thermodynamic destabilization of magnesium hydride due to Ni and Mm. The decomposition temperature of MgH 2 was reduced by more than 200 °C. The results are discussed in relation to the electronic structure and atomic size of the alloying elements and the structural variations in the alloys.

The phase structures, surface morphologies and electrochemical kinetic properties of MmNi4.50−xMnxCo0.45Al0.30 (Mm is the mischmetal, x = 0.25, 0.30, 0.35, 0.40 and 0.45) hydrogen storage alloys have been investigated in this paper. The X-ray diffraction (XRD) shows that all the alloys mainly consist of LaNi5 phase with CaCu5-type structure, which belongs to P6/mmm space group (central symmetry). Scanning electron microscopy (SEM) tests indicate that there are partial element segregations in the alloys. Meanwhile, energy dispersive spectrum (EDS) results display that the elements constituting Mm exist in the matrix phase in relatively larger proportion, while Mn, Al and Co tend to appear in precipitate phase. For the alloy with x = 0.35, the electrochemical performances, including discharge capacity, high-rate dischargeability (HRD) and cycling life, of the alloy electrode are better than that of other alloy electrodes. With the increase of Mn content, the exchange current density (I0) of the alloy electrodes first increases and then decreases, the hydrogen diffusion coefficient (D) of alloy electrodes gradually decreases. There is a linear correlation between HRD at a discharge current density of 1500 mA/g and I0.

Conventional magnesium alloy Mg–1Zn–0.4Zr and a modified version of the same alloy containing Nd-based rare earth mischmetal and Y were extruded at 400 °C to study dynamic recrystallization and its role in the microstructure and texture development. Second phase particles in the modified alloy seemed to generate new orientations other than the deformed orientation. Although this occurred within small volume fraction of the material, the respective recrystallizing grains grew up to considerable sizes consuming larger volumes of the extruded microstructure and dominating the bulk texture. The consequent mechanical behavior tested in plane strain compression at room temperature demonstrated improved strain hardening behavior and enhanced ambient formability relative to the conventional alloy due to well-scattered texture and prolonged activity of basal slip within a large volume of the deformed microstructure.

RE 3– x Mg x (Ni 0.7 Co 0.2 Mn 0.1 ) 9 ( x =0.5–1.25) alloys were prepared by induction melting and the influence of the partial substitution of RE (where RE stands for La-rich mischmetal) by Mg on the hydrogen storage and electrochemical properties of the alloys were investigated systematically. These alloys mainly consisted of three phases, La(Ni,Mn,Co) 5 phase, La 2 Ni 7 phase and Mg 2 Ni phase. The P-C-T isotherms showed that with Mg content increasing in the alloys, the hydrogen storage capacity first increased and reached the maximum capacity of 1.36 wt.% when x =1.0, and then decreased with x increasing further. Electrochemical studies revealed that the discharge capacity reached the maximum value of 380 mAh/g and the alloy electrode presented better cyclic stability when RE/Mg=2. The high rate discharge ability of the alloy electrodes was also improved by the substitution of Mg for RE. The RE 2 Mg(Ni 0.7 Co 0.2 Mn 0.1 ) 9 alloy exhibited better hydrogen absorption kinetics ( x =1.0).

The effects of La-based mischmetal (MM) and heat treatment on the microstructure and tensile properties of two different sections of A357 Al–Si casting alloy have been investigated in this study. Different concentrations (0–1 wt%) of the MM were added to the molten alloy directly. The tensile testing was employed to measure the quality index (Q.I.=UTS+150×log (elongation)) for evaluating the modification efficiency of the alloy with different MM contents. T6 heat treatment was applied before tensile testing. The results showed that the optimum levels of added mischmetal are 0.1 wt% and 0.3 wt% for thin and thick section castings respectively. A new AlSiLa intermetallic was detected through the microstructural studies at higher MM levels. Further results demonstrated that T6 heat treatment improves tensile properties of the modified alloy significantly. The differences observed in the fracture behavior were attributed to the microstructural changes as well as morphological aspects of Si particles.

The intermetallic compounds formation at interface between rare earth elements and clad material were investigated to demonstrate the effects of rare earth elements on fuel-cladding chemical interaction (FCCI) behavior. Mischmetal (70Ce-30La) and Nd were prepared as rare earth elements. Diffusion couple testing was performed on the rare earth elements and cladding (9Cr2W steel) near the operation temperature of (sodium-cooled fast reactor) SFR fuel. The performance of a diffusion barrier consisting of Zr and V metallic foil against the rare earth elements was also evaluated. Our results showed that Ce and Nd in the rare earth elements and Fe in the clad material interdiffused and reacted to form intermetallic species according to the parabolic rate law, describing the migration of the rare earth element. The diffusion of Fe limited the reaction progress such that the entire process was governed by the cubic rate law. Rare earth materials could be used as a surrogate for high burnup metallic fuels, and the performance of the barrier material was demonstrated to be effective.

NaAlH 4 has been catalyzed by MWCNT, Ce rich mischmetal (Mm), MmNi 5 and TiO 2 catalysts. The general aspect which relates every catalyst with the hydrogen storage capacity of NaAlH 4 system has been verified through XRD analysis. Interesting features like chemical reduction, grain size variation, hydrogenation/dehydrogenation and phase transformation of the catalytic species are noticed. In the case of reversible hydrogen uptake, an interesting relationship exists between the restored hydrogen capacity, crystallite size of Al (desorbed in the dehydrogenation reaction) and the applied hydrogen pressure. Thus, as far as the reversible hydrogen storage in NaAlH 4 is concerned, the mysterious role of catalyst seems to be a process of restricting the size of Al in a narrow range. The factors considered for analyzing this claim are discussed in detail.

The as-sintered sinter skin and the polished section of WC-11Co-0.4Cr3C2-0.3VC-0.2RE (RE=mischmetal with La/Ce ratio of 0.65) alloy were analyzed. It was shown that the microstructures on the skin and in the inner part of the alloy were all characterized with a WC+β+M structure, where β was a cobalt-based binder phase and M represented a RE-containing phase. There existed an inward diffusion of S atoms, which caught and fixed the Ce atoms in the alloy and an outward diffusion of La atoms during the sintering process. Consequently, the M phase was characterized with the decreased La/Ce ratio (0.59) in the inner part and the increased La/Ce ratio (1.01) on the skin. The M phase on the skin was characterized with a γ-Ce2S3 type structure. To suppress the long range migration of rare earth to the skin, S in the sintering atmosphere had to be eliminated.

It is known that heat treatment causes the spheroidization of eutectic silicon. This paper presents the influence of T6 heat treatment on the microstructures, tensile properties, and fracture behavior of the A356 alloys modified by mischmetal containing La and Ce elements. Microstructural analysis showed that the size of eutectic silicon particles was greatly reduced and the extent of speroidisation of Si particles was remarkably improved for the modified A356 alloys. Comparison between the unmodified and modified alloys suggested that the values of mean diameter, roundness, and aspect ration of eutectic silicon particles were decreased by 48.10–56.85%, 49.55–54.52%, and 13.36–30.17%, respectively. The tensile properties of the modified A356 alloys can be enhanced, especially the ductility. These could be associated with the decrease of secondary dendrite arm spacing, spheroidization of fine eutectic silicon and precipitation hardening. Scanning electron microscopy (SEM) examination indicated that the ductile fracture mechanism was responsible for the modified alloys due to the existence of a couple of fine and uniformly distributed dimples. And the eutectic silicon particles and RE-containing intermetallic compounds provide the weak locations during the fracture process.

This study reports the synthesis of NaAlH 4 by ball milling of NaH and Al mixture along with 3 mol % Mischmetal (Mm) nanocatalyst under hydrogen atmosphere. It is observed that synthesis of the intermediate phase Na 3 AlH 6 can be achieved by ball milling even under 1 atm hydrogen at room temperature. Ball milling of the NaH + Al with 3 mol % Mm with 3 atm hydrogen in excess of 40 h time did not lead to the formation of NaAlH 4 but charging of the milled material at 100 atm hydrogen pressure at 120 °C lead to formation of NaAlH 4 phase. Direct synthesis of NaAlH 4 was achieved by milling of NaH + Al with 3 mol % Mm under 100 atm hydrogen pressure. Direct synthesis is possible even without any catalyst by high pressure milling. However catalyst is required to improve the hydrogen sorption characteristics of the synthesized material. The as-prepared Mm catalyzed NaAlH 4 is also found to reversibly store hydrogen up to 4.2 wt% hydrogen. Catalytic activity is attributed to defects promoted by ball milling and catalysts.

The effect of microstructure on the phase composition and hydrogen absorption-desorption behaviour of Mg-based Mg-20Ni-8Mm (wt.%) (Mm = La-rich Mischmetal) alloys has been studied. Rapid solidification (RS) processing resulted in the formation of the high-temperature cubic modification of Mg 2 NiH 4 and the solid solution hydride Mg 2 NiH 0.3 , in the disappearance of the monoclinic modification of Mg 2 NiH 4 , as well as in a decrease in the unit cell volumes of the constituent hydride phases. The above-mentioned tendencies became more pronounced in the order “as-cast Cu-1000 >> Cu-2000”, which is explained by increased uniformity of the hydrides grain size in the hydrides with increasing solidification rate. During PCT (pressure composition temperature) tests, the Cu-1000 and Cu-2000 samples displayed the largest pressure hysteresis and the smallest slope of the higher Mg 2 NiH 4 plateau, but also the lowest hydrogen storage capacity.

Electrochemical hydriding in a 6 M KOH solution at 20 and 80 °C for 480 min was applied on a series of as-cast binary Mg–Ni and ternary Mg–Ni–Mm alloys (Mm = mischmetal containing 45% Ce, 38% La, 12% Nd and 4% Pr) containing 11–24 wt. % Ni and 0–6 wt. % Mm. The kinetics and mechanism of the hydriding process, as well as hydrogen release temperatures, were studied by glow discharge spectrometry hydrogen profiling, scanning electron microscopy, energy dispersion analysis, X-ray diffraction and mass spectrometry. A maximum hydrogen concentration of 1.1% was achieved in the eutectic MgNi24Mm5 alloy hydrided at 80 °C. In all cases, the main hydriding product was binary MgH2 hydride. Mass spectrometry revealed its destabilization due to Ni and Mm because its decomposition temperature was lowered by about 100 °C. Both nickel and mischmetal showed positive effects on hydriding and dehydriding kinetics. These effects are discussed in relation to the hydriding mechanism, electronic structure and atomic size of additives and structural variations of the alloys. Based on the H-concentration profiles, the diffusion coefficients of hydrogen were estimated. For the eutectic MgNi24Mm5 alloy, the H diffusion coefficient at 20 °C was 4 · 10−10 cm2 s−1.

The current study examines the influence of select rare earth elements; Gd, Nd, Ce, La and mischmetal (MM) on the sheet texture modification during warm rolling and annealing of a ZEK100 magnesium alloy, and the resulting formability and anisotropy during subsequent tensile testing at room temperature. It was found that all the investigated RE elements led to weak sheet textures and hence promoted enhanced ductility and reduced anisotropy over conventional Mg sheet. Gd was of a particular interest because it gave rise to a desired Mg sheet texture despite its coarsest grain size resulting in promising mechanical properties. It is suggested that solute related effects on the grain boundary migration and the relative strengths of different deformation mechanisms are responsible for altering the common concepts of recrystallization and grain growth during annealing, and the activation scenarios of slip and twinning during deformation.

The microstructural evolution of a Mg-10Ni-2Mm (molar fraction, %) (Mm=Ce, La-rich mischmetal) hydrogen storage alloys applied with various solidification rates was studied. The results show that the grain size of melt-spun ribbon is remarkably reduced by increasing the solidification rate. The microcrystalline, nanocrystalline and amorphous microstructures are obtained by applying the surface velocities of the graphite wheel of 3.1, 10.5 and 20.9 m/s, respectively. By applying the surface velocity of the graphite wheel of 3.1 m/s, the melt-spun specimen obtains full crystalline with a considerable amount of coarse microcrystalline Mg and Mg2Ni except for some Mm-rich particles. The amount of nanocrystalline phases significantly increases with increasing the surface velocity of the wheel to 10.5 m/s, and the microstructure is composed of a large amount of nanocrystalline phases of Mg and Mg2Ni particles. A mixed microstructure containing amorphous and nanocrystalline phases is obtained at a surface velocity of the wheel of 20.9 m/s. The optimal microstructure with a considerable amount of nanocrystalline Mg and Mg2Ni in an amorphous matrix is expected to have the maximum hydrogen absorption capacity and excellent hydrogenation kinetics.

Magnesium alloys have been recently developed as biodegradable implant materials, yet there has been no study concerning their corrosion fatigue properties under cyclic loading. In this study the die-cast AZ91D (A for aluminum 9%, Z for zinc 1% and D for a fourth phase) and extruded WE43 (W for yttrium 4%, E for rare earth mischmetal 3%) alloys were chosen to evaluate their fatigue and corrosion fatigue behaviors in simulated body fluid (SBF). The die-cast AZ91D alloy indicated a fatigue limit of 50MPa at 10⁷ cycles in air compared to 20MPa at 10⁶ cycles tested in SBF at 37°C. A fatigue limit of 110MPa at 10⁷ cycles in air was observed for extruded WE43 alloy compared to 40MPa at 10⁷ cycles tested in SBF at 37°C. The fatigue cracks initiated from the micropores when tested in air and from corrosion pits when tested in SBF, respectively. The overload zone of the extruded WE43 alloy exhibited a ductile fracture mode with deep dimples, in comparison to a brittle fracture mode for the die-cast AZ91D. The corrosion rate of the two experimental alloys increased under cyclic loading compared to that in the static immersion test.