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In order to develop mischmetal-based permanent magnets with a high performance/cost ratio, Si addition was employed to enhance the magnetic performance of the MM16Fe76-xCo2SixB6 (x = 0–1.5%) ribbons. The ribbons were manufactured by a melt-spinning technique at different velocities. Samples were studied in an as-cast state and after annealing. It was found that the addition of Si in the MM16Fe76-xCo2SixB6 ribbons increased the exchange interaction between Fe atoms in the 2:14:1 phase, reduced the crystal grain size, and increased the exchange coupling between the crystal grains; as a result, the magnetic properties were improved. The coercivity and Curie temperature increased with the increasing Si content from x = 0 to x = 1.5 at%, while the remanence and energy product increased with the addition of Si up to 1% and decreased with further Si addition. The best combination of magnetic properties, such as coercivity of Hc = 8.9 kOe, remanence Mr = 98 emu/g, Curie temperature Tc = 257 °C, and energy product (BH)max = 13.84 MGOe, were obtained in ribbons with 1.0 at. % Si. Thus, it is demonstrated that the addition of Si leads to an improvement of the magnetic properties of MM16Fe76-xCo2SixB6 ribbons, making them good candidates as precursors for the preparation of permanent magnets with an energy product between that of ferrites and Nd-Fe-B magnets. [ABSTRACT FROM AUTHOR]

The microstructures and mechanical properties of Mg–3Sn–0.1Ca–xMM (mischmetal, x = 0.3, 0.6, and 0.9 wt.%) alloys were investigated. Optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) were used to characterize the microstructures and phase constitutions of the cast and rolled alloys. Room temperature tensile tests were conducted to obtain the mechanical properties and macro-textures to evaluate the texture weakening effect results of the MM. The results show that an abundance of second phase formed, confirmed as the (Ca,MM)MgSn phase, and the volume fraction increased with the increasing MM addition. The tensile yield strength of the as-cast alloys increased with the MM addition, but the elongation decreased. All of the rolled Mg–3Sn–0.1Ca–xMM alloys showed a strong basal texture, and only slightly decreased in intensity after annealing treatment due to the particle-stimulated nucleation of recrystallization. The as-annealed Mg–3Sn–0.1Ca–0.6MM alloys exhibited the highest tensile strengths of 266.5 ± 3.3 MPa and 136.1 ± 3.7 MPa, which are mainly ascribed to grain refinement strengthening, Orowan strengthening and texture strengthening. [ABSTRACT FROM AUTHOR]

In order to develop mischmetal-based permanent magnets with a high performance/cost ratio, Si addition was employed to enhance the magnetic performance of the MM16Fe76-xCo2SixB6 (x = 0–1.5%) ribbons. The ribbons were manufactured by a melt-spinning technique at different velocities. Samples were studied in an as-cast state and after annealing. It was found that the addition of Si in the MM16Fe76-xCo2SixB6 ribbons increased the exchange interaction between Fe atoms in the 2:14:1 phase, reduced the crystal grain size, and increased the exchange coupling between the crystal grains; as a result, the magnetic properties were improved. The coercivity and Curie temperature increased with the increasing Si content from x = 0 to x = 1.5 at%, while the remanence and energy product increased with the addition of Si up to 1% and decreased with further Si addition. The best combination of magnetic properties, such as coercivity of Hc = 8.9 kOe, remanence Mr = 98 emu/g, Curie temperature Tc = 257 °C, and energy product (BH)max = 13.84 MGOe, were obtained in ribbons with 1.0 at. % Si. Thus, it is demonstrated that the addition of Si leads to an improvement of the magnetic properties of MM16Fe76-xCo2SixB6 ribbons, making them good candidates as precursors for the preparation of permanent magnets with an energy product between that of ferrites and Nd-Fe-B magnets.

The effects of solo rare earth Y and combined rare earth Y and Sm elements on the microstructure and mechanical properties of AZ91D magnesium alloy were studied by controlling variable method.The grain refinement mechanism of rare earth elements on AZ91D alloy was analyzed. The results show that the effect of combined addition of rare earth Y and Sm on AZ91D alloy is better than that of solo addition of rare earth Y significantly. More effective heterogeneous nucleation sites for α-Mg are achieved by adding Y and Sm to AZ91D alloy produced bulk phase Al2Y and acicular phase Al2Sm. When the addition content is 0.8% (mass fraction) Y and 1.0%Sm, the α-Mg grain size is the smallest and most uniform. The hardness, tensile strength and elongation of the alloy are 67.42HV, 153.37 MPa and 3.62% respectively, the mechanical properties of as-cast AZ91D alloy at room temperature are improved. However, the mechanical properties of the AZ91D alloy at room temperature decrease after exceeding this optimum addition.

The microstructures and mechanical properties of Mg–3Sn–0.1Ca–xMM (mischmetal, x = 0.3, 0.6, and 0.9 wt.%) alloys were investigated. Optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) were used to characterize the microstructures and phase constitutions of the cast and rolled alloys. Room temperature tensile tests were conducted to obtain the mechanical properties and macro-textures to evaluate the texture weakening effect results of the MM. The results show that an abundance of second phase formed, confirmed as the (Ca,MM)MgSn phase, and the volume fraction increased with the increasing MM addition. The tensile yield strength of the as-cast alloys increased with the MM addition, but the elongation decreased. All of the rolled Mg–3Sn–0.1Ca–xMM alloys showed a strong basal texture, and only slightly decreased in intensity after annealing treatment due to the particle-stimulated nucleation of recrystallization. The as-annealed Mg–3Sn–0.1Ca–0.6MM alloys exhibited the highest tensile strengths of 266.5 ± 3.3 MPa and 136.1 ± 3.7 MPa, which are mainly ascribed to grain refinement strengthening, Orowan strengthening and texture strengthening.

The microstructure and mechanical properties of butt-joints produced by linear friction stir welding of similar plates of as-cast ZK60 and modified ZK60 with 1.5 wt.% RE (ZK60–1.5RE) are investigated. The thermomechanical affected zone is investigated in both advancing and retrieving sides, and the microstructure is compared to the base metal and the stirred zone. Electron backscattered diffraction measurements provide the average microstructural features of the transformed microstructure. The mechanical properties are assessed using hardness, tensile testing, and surface residual stress measured using X-ray diffraction. Higher torque and heat input are obtained for the ZK60–1.5RE compared to the ZK60. The thermomechanical affected zone is notably larger for the ZK60 compared to the ZK60–1.5RE. A gradient microstructure is formed in thermomechanical affected zones where deformed grains are progressively more recrystallised towards the stirred zone. There is no visible interface between the thermomechanical affected zone and the stirred zone. A fine and partially recrystallised microstructure is formed in the stirred zone. The retrieving side of the ZK60–1.5RE has a slightly more refined microstructure compared to the other investigated zones. Anisotropy measured with increment in the maximum intensity of the (0001) increases towards to stirred zone. The formed microstructure is correlated with the role of twinning, recovery, static, and dynamic recrystallisation that can occur during friction stir welding. Twinning and grains with large misorientation spread are more pronounced in the thermomechanical affected zone and regions towards the base metal. Sharp low angle grain boundaries are observed towards the stirred zone. From refined recrystallised grains decorating the grain in the thermomechanical affected zone, a mosaic-like of low and high angle grain boundaries are observed in the stirred zone. The joints have comparable surface residual stresses. The friction stir welding improved the ductility and strength of the as-cast ZK60–1.5RE alloy since the tensile samples fractured in the BM.

Mg-Zn-Zr (ZK) alloys exhibit notably high mechanical strength amongst all magnesium alloy grades. However, due to the formation of low melting point Mg3Zn7-precipitates, these alloys are susceptible to hot cracking, thus compromising their metallurgical processing. The addition of rare earths to ZK alloys is an alternative to form higher melting point intermetallic compounds, speed up dynamic recrystallization, refine grain size, enhance corrosion resistance and extend the service temperature due to improved creep resistance. This work deals with the effect of Ce-base mischmetal addition on the hot rolling behaviour of as-cast ZK60 alloy. The microstructure investigation conducted using electron microscopy and X-Ray diffraction shows that precipitation of Mg7Zn3 intermetallics occur during hot rolling, whereas no further precipitation is observed for the ZK60-Mm alloys. The fragmentation of the intermetallic compounds occur during hot rolling and finer particles of Mg7Zn3 are observed for the ZK60, whereas Mg7Zn3 and MgZn2Ce intermetallics are formed in the alloy modified with mischmetal addition. A higher fraction of dynamically recrystallized grains is observed for the ZK60-Mm in comparison to the ZK60. Continuous recrystallization takes place in ZK60 with the formation of sub-grains near to the intermetallics and the addition of mischmetal promotes the occurrence of discontinuous recrystallization with the nucleation of new grains close to the precipitates. The mechanical strength and, in particular, the ductility of the hot-rolled alloys are notably improved when compared to the same alloys in the as-cast condition. The mechanical strength is, however, higher for the ZK60 alloy. Less solid solution strengthening, softer MgZn2Ce intermetallics and more extensive recrystallization contribute to reduce the mechanical strength of ZK60-Mm. Failure in both alloys are initiated at coarse intermetallics and propagate through intermetallic-rich regions.

The microstructure and mechanical properties of butt-joints produced by linear friction stir welding of similar plates of as-cast ZK60 and modified ZK60 with 1.5 wt.% RE (ZK60–1.5RE) are investigated. The thermomechanical affected zone is investigated in both advancing and retrieving sides, and the microstructure is compared to the base metal and the stirred zone. Electron backscattered diffraction measurements provide the average microstructural features of the transformed microstructure. The mechanical properties are assessed using hardness, tensile testing, and surface residual stress measured using X-ray diffraction. Higher torque and heat input are obtained for the ZK60–1.5RE compared to the ZK60. The thermomechanical affected zone is notably larger for the ZK60 compared to the ZK60–1.5RE. A gradient microstructure is formed in thermomechanical affected zones where deformed grains are progressively more recrystallised towards the stirred zone. There is no visible interface between the thermomechanical affected zone and the stirred zone. A fine and partially recrystallised microstructure is formed in the stirred zone. The retrieving side of the ZK60–1.5RE has a slightly more refined microstructure compared to the other investigated zones. Anisotropy measured with increment in the maximum intensity of the (0001) increases towards to stirred zone. The formed microstructure is correlated with the role of twinning, recovery, static, and dynamic recrystallisation that can occur during friction stir welding. Twinning and grains with large misorientation spread are more pronounced in the thermomechanical affected zone and regions towards the base metal. Sharp low angle grain boundaries are observed towards the stirred zone. From refined recrystallised grains decorating the grain in the thermomechanical affected zone, a mosaic-like of low and high angle grain boundaries are observed in the stirred zone. The joints have comparable surface residual stresses. The friction stir welding improved the ductility and strength of the as-cast ZK60–1.5RE alloy since the tensile samples fractured in the BM. [ABSTRACT FROM AUTHOR]

Most of the recent work focused on improving the dimensionless figure-of-merit, ZT, of p-type skutterudites uses one or two fillers to tune the electrical and thermal properties. Considering the fact that the different fillers with varying atomic mass and ionic radii can vibrate with different amplitudes to scatter phonons of different mean free paths, we synthesized misch metal filled p-type skutterudites Mm0.9Fe4-xCoxSb12 (where Mm is La0.25Ce0.5Pr0.05Nd0.15Fe0.03, called misch metal). The samples were synthesized by hot pressing nano-powder made by ball milling the annealed ingot of Mm0.9Fe4-xCoxSb12 with varying concentration of cobalt, x. By tuning the Fe/Co ratio, we achieved a thermal conductivity of ~2W m-1 K-1 at room temperature and ~2.3W m-1 K-1 at about 530 °C and a power factor of ~30 μW cm-1 K-2 at about 425°C in Mm0.9Fe3.1Co0.9Sb12, leading to a peak ZT ~1.1 at about 425°C. The nano-indentation experiment reveals that hardness and elastic modulus of the material is about 4.2 GPa and 116 GPa, respectively. [ABSTRACT FROM AUTHOR]

Most of the recent work focused on improving the dimensionless figure-of-merit, ZT, of p-type skutterudites uses one or two fillers to tune the electrical and thermal properties. Considering the fact that the different fillers with varying atomic mass and ionic radii can vibrate with different amplitudes to scatter phonons of different mean free paths, we synthesized misch metal filled p-type skutterudites Mm0.9Fe4-xCoxSb12 (where Mm is La0.25Ce0.5Pr0.05Nd0.15Fe0.03, called misch metal). The samples were synthesized by hot pressing nano-powder made by ball milling the annealed ingot of Mm0.9Fe4-xCoxSb12 with varying concentration of cobalt, x. By tuning the Fe/Co ratio, we achieved a thermal conductivity of ~2W m-1 K-1 at room temperature and ~2.3W m-1 K-1 at about 530 °C and a power factor of ~30 μW cm-1 K-2 at about 425°C in Mm0.9Fe3.1Co0.9Sb12, leading to a peak ZT ~1.1 at about 425°C. The nano-indentation experiment reveals that hardness and elastic modulus of the material is about 4.2 GPa and 116 GPa, respectively. [ABSTRACT FROM AUTHOR]

Mg-Zn-Zr (ZK) alloys exhibit notably high mechanical strength amongst all magnesium alloy grades. However, due to the formation of low melting point Mg 3 Zn 7 -precipitates, these alloys are susceptible to hot cracking, thus compromising their metallurgical processing. The addition of rare earths to ZK alloys is an alternative to form higher melting point intermetallic compounds, speed up dynamic recrystallization, refine grain size, enhance corrosion resistance and extend the service temperature due to improved creep resistance. This work deals with the effect of Ce-base mischmetal addition on the hot rolling behaviour of as-cast ZK60 alloy. The microstructure investigation conducted using electron microscopy and X-Ray diffraction shows that precipitation of Mg 7 Zn 3 intermetallics occur during hot rolling, whereas no further precipitation is observed for the ZK60-Mm alloys. The fragmentation of the intermetallic compounds occur during hot rolling and finer particles of Mg 7 Zn 3 are observed for the ZK60, whereas Mg 7 Zn 3 and MgZn 2 Ce intermetallics are formed in the alloy modified with mischmetal addition. A higher fraction of dynamically recrystallized grains is observed for the ZK60-Mm in comparison to the ZK60. Continuous recrystallization takes place in ZK60 with the formation of sub-grains near to the intermetallics and the addition of mischmetal promotes the occurrence of discontinuous recrystallization with the nucleation of new grains close to the precipitates. The mechanical strength and, in particular, the ductility of the hot-rolled alloys are notably improved when compared to the same alloys in the as-cast condition. The mechanical strength is, however, higher for the ZK60 alloy. Less solid solution strengthening, softer MgZn 2 Ce intermetallics and more extensive recrystallization contribute to reduce the mechanical strength of ZK60-Mm. Failure in both alloys are initiated at coarse intermetallics and propagate through intermetallic-rich regions. [ABSTRACT FROM AUTHOR]

• Off-stoichiometric La x MM x Fe 10.2 Co 1.0 Si 1.8 alloys were prepared. • The Curie temperature of the alloys is tunable near room temperature. • The isothermal entropy change is improved by adding excessive rare earth. • The alloys exhibit large magnetocaloric effect and relative cooling power. NaZn 13 -type La(Fe, Si) 13 -based alloys have been considered as one of the most promising candidates for magnetic refrigeration application near room temperature. In this paper, we present the structural and magnetic properties of off-stoichiometric alloys with composition of La x MM x Fe 10.2 Co 1.0 Si 1.8 (x = 0.50, 0.55, 0.60, 0.65 and 0.70), in which MM stands for La-Ce-Pr-Nd mischmetal. Rietveld refinement of the XRD patterns indicated that adding excessive rare earth suppressed the precipitation of α-Fe phase, but resulted in the increase of secondary rich-rare-earth phases. The Curie temperature changed slightly with x around room temperature. For a field change of 3 T, the off-stoichiometric alloys exhibit maximum isothermal entropy change in a range of 5.1 ∼ 6.5 J/kgK, which is higher than that of the stoichiometric alloy. The corresponding values of relative cooling power are found to be 221 ∼ 253 J/kg. The present study provides some scientific guidance for developing magnetic refrigerants near room temperature. [ABSTRACT FROM AUTHOR]

The combined addition of small amounts of Ca and Y to Mg–Al–Zn alloys has recently been found to greatly improve the ignition resistance, corrosion resistance, and mechanical properties of these alloys. However, Mg–Al–Zn–Ca–Y alloys with high Al content show poor extrudability, which is an obstacle to their use as extruded components in industrial applications. This study aims to improve the extrudability of a Mg–Al–Zn–Ca–Y alloy through the addition of a small amount of mischmetal (MM). To this end, a trace amount (0.5 wt%) of Ce-rich MM is added to a Mg–9Al–0.8Zn–0.9Ca–0.6Y (AZXW9110) alloy. MM addition leads to significant grain refinement of the homogenized billet, from 326 to 180 μm. When the MM-added alloy is extruded into a sheet at 350 °C with an extrusion ratio of 22.9, the maximum ram speed at which it is extrudable without the occurrence of hot cracking is 12 mm/s, substantially higher than the 2 mm/s possible without MM addition. The Ce and La atoms decomposed from the MM are dissolved in the Mg17Al12, Al8Mn4Y, Al2Ca, and Al2Y phases, apparently leading to an increase in the thermal stability of the phases and, consequently, to an improvement in the AZXW9110 alloy's extrudability. At ram speeds above 2 mm/s, many small-sized cracks form at the edges of the extruded AZXW9110–0.5MM sheets. As the ram speed increases up to 6 mm/s, the number density of edge cracks gradually increases while their average spacing decreases, but beyond 6 mm/s both remain almost unchanged. [ABSTRACT FROM AUTHOR]

Abstract MgH2 + mischmetal nanostructured composite was synthesized from MgH2 plus 6 and 10 wt% of mischmetal by ball-milling at various times. XRD studies revealed that cerium hydride was produced during the milling in all samples. Sievert test results indicated that the samples containing 6 wt% of mischmetal showed a higher desorption compared with the ones containing 10 wt% of mischmetal. The high amount of cerium hydride in the samples may be the reason, while hydrogen desorption properties decreased by adding more catalyst. Furthermore, BET results showed that the addition of the catalyst to the samples resulted in agglomerate formation in shorter milling times. The agglomerate formation increased with adding more amounts of mischmetal, thus decreasing the hydrogen desorption properties of the composite. The best results were obtained from the 30 h-milled sample containing 6 wt% of catalyst. The on-set desorption temperature of this sample was 100 °C lower than that of as-received MgH2.

In this study, a commercial Mg-based ZK60 alloy was modified with 2.5 wt% mischmetal (ZK60-2.5 wt%Mm) and further processed by cold rolling followed by manual filing. The chips obtained by manual filing process were collected from the as cast (AC) and the cold rolled (CR) materials. The hydrogen storage properties were evaluated by kinetics measurements at 350 °C. A full microstructural characterization including optical, scanning and transmission electron microscopy (MO, MEV and TEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) was performed in the samples. For the first absorption of both filed samples the H storage capacity showed a value around 6.0 wt% after 1 h while for the CR sample it was close to 1.25 wt% after the same time. The manual filing produced samples with higher hydrogenation kinetics compared with that of the CR sample. Besides, their hydrogen storage capacity was maintained close to the theoretical value (6.75 wt%). The breakage and pulverization of the intermetallic phases gave the chips from the CR alloy the faster hydrogenation kinetics, especially for H-desorption. • The ZK60-2.5 wt%Mm alloy gives rise to high melting point precipitates. • Addition of mischmetal improves the thermal stability of ZK60 alloy. • The filing produces chips with high surface/volume fraction. • The filing samples have much better absorption and desorption kinetics. • Manual filing is low cost and easy to industrialize. [ABSTRACT FROM AUTHOR]

The isotropic nanocrystalline [(PrNd)0.8MM0.2]29.8Fe68.7Al0.1Cu0.12Co0.88B magnets (MM: mischmetal) were prepared by single-main phase and double-main phase methods using spark plasma sintering (SPS). Melt-spinning method was used to prepare initial powder and avoid component deviations caused by longtime ball milling. The magnetic properties of the magnet prepared by double-main phase method (called double-main phase magnet, DMP magnet) are remanence of Br = 0.75 T, intrinsic coercivity of Hcj = 909.83 kA·m−1, maximum magnetic energy product of (BH)max = 95.48 kJ·m−3, which are better than those of the magnet prepared by single-main phase method (called single-main phase magnet, SMP magnet). The diffraction peaks of the main phase of DMP magnet split in X-ray diffractometer (XRD) pattern, indicating that R2Fe14B phases with different distributions of La/Ce elements exist in the magnet. This speculation is confirmed by transmission electron microscopy (TEM) observation. The La/Ce-rich main phase and La/Ce-lean main phase are present in DMP magnets. The heterogeneity of rare earth elements suppresses the magnetic dilution effect in DMP magnet, and the magnetic properties are improved. Though the DMP magnet contains different main phases, it presents unitary Curie temperature (TC) of 577 K, which is higher than that of SMP magnet. This result suggests that the TC of the magnets can be promoted by double-main phase method and SPS. [ABSTRACT FROM AUTHOR]

Microstructure and mechanical properties are studied for five cast, coarse-grained intermetallic alloys: binary Al 11 Ce 3 and Al 11 La 3 , ternary Al 11 (Ce 0.75 La 0.25) 3 and Al 11 (Ce 0.5 La 0.5) 3 , and quaternary Al 11 (Ce 0.54 La 0.27 Nd 0.19) 3 with mischmetal composition. All compounds exhibit a single phase indicating a solid solution among the three rare-earth elements (RE=Ce, La, and Nd) on the Ce sublattice of Al 11 RE 3 , in disagreement with Thermo-Calc prediction of segregation of Ce and (La, Nd) into two insoluble compounds. The lattice parameters of this orthorhombic Immm-structured α-Al 11 RE 3 phase increase as La concentration increases, while the α-β phase transformation temperature decreases. The five Al 11 RE 3 compounds show very similar (i) propensity for twinning, (ii) high hardness (4.1–4.3 GPa), and (iii) low indentation fracture toughness (0.48–0.65 MPa m1/2). The Al-Al 11 RE 3 interface lattice mismatches, as calculated for two stable interface orientations, have comparable values across all examined compounds. These similarities imply that these Al 11 RE 3 compounds will exhibit comparable strengthening and coarsening resistance in Al-RE-based eutectic alloys, thus positioning them as economically- and environmentally-favorable alternatives to the well-developed binary Al 11 Ce 3 compound formed in current eutectic Al-Ce alloys. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper is discussed the effect of the inoculant mischmetal addition on the microstructure of the magnesium alloy AZ91. The concentration of the inoculant was increased in the samples within the range from 0.1% up to 0.6%. The thermal process was performed with the use of Derivative and Thermal Analysis (DTA). A particular attention was paid to finding the optimal amount of the inoculant, which causes fragmentation of the microstructure. The concentration of each element was verified with use of a spark spectrometer. In addition, the microstructures of every samples were examined with the use of an optical microscope and also was performed an image analysis with a statistical analysis using the NIS-Elements program. The point of those analyses was to examine the differences in the grain diameters of phase αMg and eutectic αMg+γ(Mg17Al12) in the prepared samples as well as the average size of each type of grain by way of measuring their perimeters. This paper is the second part of the introduction into a bigger research on grain refinement of magnesium alloys, especially AZ91. Another purpose of this research is to achieve better microstructure fragmentation of magnesium alloys without the relevant changes of the chemical composition, which should improve the mechanical properties. [ABSTRACT FROM AUTHOR]

The article presents the results of primary crystallization, wear resistance and SEM studies of chromium cast iron inoculated with ferrotitanium and rare earth elements as a mischmetal inoculating mixture. Thermal-derivative analysis method was used to conduct studies of primary crystallization in two types of testers, namely ATD-C and ATD-Is, reflecting two different cooling speeds. Wear resistance tests were performed with the use of modified pin-on-disk method on Tribotester 3-POD device, where the samples were moving in circular motion in metal-mineral friction system. Silicon carbide was used as a counter sample. The studies allowed to determine the influence of selected inoculants on the microstructure and wear resistance of the studied samples. All characteristic crystallization temperatures of samples casted into ATD-Is testers increased, as well as wear resistance of each inoculated samples compared to the non-inoculated sample. It was proven that TiC and REE compounds are effective inoculants for chromium carbides and that REE compounds can work as underlay for TiC crystallization. [ABSTRACT FROM AUTHOR]

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Abstract 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. Highlights • Trace Ca addition weakens basal texture and increases room-temperature stretch formability in Mg-4Zn-1MM alloy sheet. • Ca-containing Mg-4Zn-1MM-0.1Ca alloy sheet causes co-segregation of Zn and Ca atoms to grain boundaries. • Co-segregation of Zn and Ca prevents formation of strong basal texture during hot-rolling. [ABSTRACT FROM AUTHOR]

In this work, the effect of mischmetal addition on the microstructural, physical and mechanical properties of rapidly solidified (Al90Ni8Zr2)(100−x)MMx (x = 0-6) alloys has been studied. In this respect, various as-spun ribbons were prepared by the single-roller melt-spinning process at a quenching wheel speed of 43 m/s. The results obtained showed that mischmetal had a strong effect on the control of amorphicity of the alloy during melt-spinning process. TEM and XRD results revealed the presence of two phases, nanocrystalline α-Al and amorphous phase of Al90Ni8Zr2 alloy compared with those of MM-added samples with an amorphous structure. This is believed to be related to the increase in glass-forming ability due to the addition of mischmetals to the alloy. The average crystallite size obtained for MM-free sample was in the range of 30 nm as confirmed by XRD and TEM data. Phase separation and formation of second phase were observed for 6 at.% MM-added sample in the as-spun state. DSC results revealed that glass transition and crystallization temperatures increased with the increase in mischmetal in Al90Ni8Zr2 system. Further, it was seen that the maximum microhardness value was obtained for the 4 at.% MM-added samples (4.72 GPa). [ABSTRACT FROM AUTHOR]

The effect of 2 mass% rare earth elements (RE) as in mischmetal state on the structure, thermal behaviour and mechanical properties of Mg-xLi-4Al (x = 4, 8 and 12 by mass percentage). The thermo-derivative analysis was implemented using the UMSA platform (Universal Metallurgical Simulator and Analyzer) with cooling rate approx. ≈ 0.6 °C s−1 that correspond to natural cooling. Microstructural evaluations were identified by X-ray diffraction, scanning electron microscopy, light microscope and energy-dispersive X-ray spectroscopy. Obtained results from the thermal derivative analysis allowed determining the solidification pathways for Mg-Li-Al-RE alloy. The addition of grain refinement causes changes in crystallisation process. The addition of RE elements affected an enhancement in mechanical properties, which was associated with the development of intermetallic compounds; the maximum increases in hardness at level 240% was observed for single α-phase alloy and at level 19% for α + β alloy. [ABSTRACT FROM AUTHOR]

Misch metal (Mm), consisting of Ce and La, was added to Ti-45Al-3Mo-2Nb alloys in order to investigate phase transformation and microstructural changes. The pseudo-binary phase diagram was estimated via PANDAT software™. The addition of Mm caused a decrease in both the fractions of α2/γ lamella and the β0 phase, and served as an important factor for a collapse of lamellar structures. In addition, Mm significantly decreased the colony size of the alloy, resulting in an increase in high-temperature tensile yield strength of ~ 40% for the alloys with 0.3 at% Mm at 800 °C. It appears that the addition of Mm affects the phase stability and increase the proportion of the γ phase. The microstructural changes, with respect to Mm additions, were discussed in terms of structural observations during isothermal heat treatments. [ABSTRACT FROM AUTHOR]

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 Mg 7 Zn 3 intermetallic, which is the main precipitate for ZK60 alloy, has hardness 20% higher than the MgZn 2 Ce intermetallic that is precipitated with the mischmetal addition and partly removes solute from the Mg-solid solution. [ABSTRACT FROM AUTHOR]

In this paper, the Rare-earth Iron Boron (RE-Fe-B) magnets were fabricated successfully by using the double main phase method through mixing the Neodymium Iron Boron (Nd-Fe-B) powders and Misch-metal Iron Boron (MM-Fe-B) powders with different ratio. Aiming at the nanocrystalline RE 2 Fe 14 B magnets prepared by using spark plasma sintering technology, phase structure and magnetic properties were investigated. It is found that the Misch-metal (MM) alloys promote the domain nucleation during the the process of magnetization reversal and then damage the coercivity ( H cj ) of isotropic RE 2 Fe 14 B magnets, while the H cj could still remain more than 1114.08 kA/m when the mass proportion of MM (simplified as: “a”) is 30%. Curie temperature and phase structure were also researched. Two kinds of mixed-solid-solution (MSS) main phases with different Lanthanum (La) and Cerium (Ce) content were believed to be responsible for the two curie temperature of the RE 2 Fe 14 B magnets with “a” ≥20%. This is resulted from the inhomogeneous elemental distribution of RE 2 Fe 14 B phase. [ABSTRACT FROM AUTHOR]

Two magnets with the same nominal composition of (MM 0.3 Nd 0.7 )-Fe-B (Marked as A) and [(La 0.27 Ce 0.53 Pr 0.03 Nd 0.17 ) 0.3 Nd 0.7 ]-Fe-B (Marked as B) were prepared using traditional powder metallurgical process, respectively. In order to point out the difference between two magnets, the magnetic properties, microstructure and magnetic domain of both magnets were investigated. Both magnets have the same elements, but different raw materials of misch-metal (MM) and La/Ce/Pr/Nd pure metal, which induces different magnetic properties. The magnet A with B r of 13.1 kGs, H cj of 7.6 kOe, (BH) max of 37.8 MGOe and magnet B with B r of 13.4 kGs, H cj of 5.8 kOe, (BH) max of 34.5 MGOe are obtained. Although both magnets have the similar B r , magnet A has higher coercivity than that of magnet B. According to refined results of characteristic X-ray diffraction peaks, there is a hard magnetic main phase with higher magnetic anisotropy field ( H A ) in magnet A and opposite case happens on magnet B. SEM images demonstrate that magnet A has more continuous RE-rich phase and smaller grain size compared to that of magnet B, which contributes to enhancing the coercivity. In addition, two main phases of [Nd 0.82 (La, Ce) 0.18 ]-Fe-B and [Nd 0.75 (La, Ce) 0.25 ]-Fe-B were detected by the EDX calculation, and the two main phases in both magnets were observed by magnetic domains again. Compared to magnet B, 2:14:1 main phases in magnet A contain more [Nd 0.82 (La, Ce) 0.18 ]-Fe-B main phases and less [Nd 0.75 (La, Ce) 0.25 ]-Fe-B main phases, which also leads to higher coercivity due to the different H A among Nd 2 Fe 14 B, La 2 Fe 14 B and Ce 2 Fe 14 B phases. Therefore, it is concluded that MM substitution could exhibit better magnetic properties than (La 0.27 Ce 0.53 Pr 0.03 Nd 0.17 )-metal substitution. Furthermore, applications of MM are beneficial to fabricate (MM, Nd)-Fe-B permanent magnets with lower cost. [ABSTRACT FROM AUTHOR]

In this study, the effect of wheel speed and mischmetal (MM) content on the magnetic properties of MMFeB ribbons was investigated. The samples were prepared via direct solidification technique. The nominal composition of the alloy ingots is MMFeB with x varying from 9 to 15 in steps of 2. Experimental results show the overall magnetic properties of the ribbons. Analysis of the results shows that the magnetic properties first improve and then degrade with the wheel speed and MM content increasing. Increase in MM content leads to better formation of crystal texture in the ribbons, indicating that the α-Fe phase might undermine the formation of crystal texture. Magnetic properties results show that the coercivity of the ribbons rises with an appropriate increase in both MM content and wheel speed during melt-spun process. The strongest magnetic properties of the ribbons (remanence of M = 0.72 T, intrinsic coercivity of H = 352.58 kA·m, and maximum energy product of ( BH) = 72.14 kJ·m) are obtained for compositions where x = 13 and a wheel speed of v = 20 m·s. Graphical Abstract: The variation in maximum remanence ( M ), coercivity ( H ), and maximum energy product (( BH)) values were analyzed as a function of wheel speed for the MMFeB melt-spun ribbons. All of the ribbons' magnetic properties ( M , H , and ( BH)) first increase as the wheel speed increases up to 20 m·s and then decrease gradually. The best magnetic properties are obtained at a wheel speed of 20 m·s, achieving M value of 0.72 T, H value of 352.58 kA·m, and ( BH) value of 72.14 kJ·m. [ABSTRACT FROM AUTHOR]

Utilization of the relatively abundant and inexpensive (Ce,La)-mischmetal in manufacturing die-upset R–Fe–B magnets (R = rare earth) from melt-spun nanocrystalline alloys was attempted via: 1) the standard single-alloy process; 2) the diffusion of Nd and Pr from low-melting-temperature alloys blended into the magnet; and 3) the diffusion of Nd and Pr by infiltrating the magnet through its surface. No practically viable magnetic properties could be obtained without the introduction of Nd(Pr). Blending with the (Nd,Pr)-rich alloys was found to be less efficient for the development of coercivity than the single-alloy process; so was the infiltration of those precursors which had been alloyed with 0.5 at.% Ga. More efficient than the single-alloy process was infiltration of those precursors which had been alloyed with 2 at.% Si or with 1 at.% Zn. Coercivities of 7–10 kOe and energy products of 17–20 MGOe were obtained for magnets having 43%–55% of the R elements represented by Ce0.65La0.35 and containing overall 7.5–9.7 at.% Nd(Pr). The coercivity of the significantly hyper-stoichiometric (17–19 at.% R) (Ce,La)-containing alloys was found to decline 80% or more as a result of the deformation process, but partially recover after subsequent annealing. The latter improvement is likely to be caused by redistribution of the R-rich phases. [ABSTRACT FROM AUTHOR]

Magnetic and structural properties of Misch Metal (MM)-Fe-B alloys, were examined in the melt-spun ribbons. Melt-spun MM-Fe-B samples were prepared at the surface velocities of 18–30 m/s. Crystalline structure and their room-temperature magnetization characteristics were analyzed, and the optimum surface velocity of 20 m/s and nominal composition of MM 13 Fe 81 B 6 were obtained. Microstructural analyses indicate that the grain size is approximately 30–50 nm in the alloys with the optimum characteristics. In the MM 16 Fe 78 B 6 alloys, Pr-rich and La-rich phases concentrated on grain boundaries, which resulted in the coercivity augment with the increase of MMFe 2 content. Dependence of coercivity on applied magnetic field suggested that the mechanism of coercivity in moderate MM-content samples was inhomogeneous domain wall pinning type. The melt-spun ribbons in the optimum condition exhibit a coercive force of 6.9 kOe and an energy product of 8.5 MGOe, which can be used as the potential isotropy magnetic powders in the bonded magnets. [ABSTRACT FROM AUTHOR]

The non-isothermal kinetics of crystallization in amorphous Al 86 Ni 10 Zr 2 MM 2 (MM: misch metal) alloy have been studied utilizing differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Non-isothermal DSC experiment showed that the crystallization process of the Al 86 Ni 10 Zr 2 MM 2 alloy take place in three steps. The first crystallization step is corresponding to the precipitation of fcc-Al nanoparticles. The XRD results showed that partially overlapped second and third peaks are related to precipitation of Al 11 MM 3 , Al 3 Ni and Al 3 Zr phases. Utilizing Kissinger method, the mean value of activation energy has been evaluated for all crystallization steps. The results showed that the crystallization activation energy for first, second and third crystallization step are 251.6 ± 6.2, 270.4 ± 7.1 and 289.6 ± 3.9 kJ/mol respectively. The obtained mean value of the Avrami exponent for first crystallization stage revealed that the crystallization mechanism was a decreasing nucleation rate crystallization process in diffusion control regime. [ABSTRACT FROM AUTHOR]

The effect of calcium, manganese and cerium mischmetal additions on the mechanical properties of the extruded Mg-6Zn-1Y (wt%) alloy reinforced by quasicrystalline I-phase has been investigated. The tensile behaviour at room temperature can be rationalized on the basis of microstructural changes induced by the different elements added to the ternary alloy. The highest yield stress value corresponds to the material modified with cerium-rich mischmetal. Manganese addition leads to the best balance between strength and ductility while calcium addition has a negligible effect on the mechanical properties of ternary alloy. The analysis of the contributions of the different strengthening mechanisms operating during deformation reveals that grain size refinement is the main hardening contribution in all alloys mechanism followed by the strengthening due to coarse second phases. The hardening due to basal texture conferred by the existence of coarse non-recrystallized grains depends on the overall hardening induced by the rest of strengthening mechanisms. [ABSTRACT FROM AUTHOR]

The influence of mischmetal (lanthanum and cerium) on the microstructure and mechanical properties of Mg-9Li-3Al- x RE ( 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, Al 4 RE phase is formed, the content of Mg 17 Al 12 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- x RE alloys are improved. However, with increasing mischmetal content, the size of Al 4 RE phase increases and the mechanical properties decrease. In extruded alloys, Al 4 RE 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. [ABSTRACT FROM AUTHOR]

Cigarette smoking is a well-recognized cause of lung cancer and other diseases and is a major contributor to indoor air pollution in numerous settings worldwide. Most cigarette lighters use rare earth element (REE) mischmetal in their flints in order to aid ignition, and these lighters thus have pyrophoric properties. REE particulate emitted from these lighters presents a complexity in the role of health of smokers that has yet to be explored fully. Furthermore, these particles are likely present in numerous urban settings and contribute to the complexities of urban geochemistry. Details of the material properties of rare earth element (REE) particulate derived from smoking lighters are determined first the first time. Particulate was investigated using back-scatter detection scanning electron microscopy techniques and transmission electron microscopy techniques. Several particle types were observed and demonstrate a diverse range of size and textures, many of which are previously not documented and are much smaller than previous basic scanning electron microscopy investigations. These include irregularly shaped fragments of mischmetal, micrometer-scale spherules, aggregates of nanospherules, and platy sponge-like nanoparticles. All of these particles have significant REE content, and most are of a particle size that can be deposited deep in the lung. The available literature regarding toxicity of REEs and the material science data presented here argues very strongly for cause for concern. [ABSTRACT FROM AUTHOR]

The effect of replacing Nd with misch metal (MM) on magnetic properties and thermal stability has been investigated on melt-spun (Nd1-xMMx)13.5Fe79.5B7 ribbons by varying x from 0 to 1. All of the alloys studied crystallize in the tetragonal 2:14:1 structure with single hard magnetic phase. Curie temperature (Tc), coercivity (Hcj), remanence magnetization (Br) and maximum energy product ((BH)max) all decrease with MM content. The melt-spun MM13.5Fe79.5B ribbons with high ratio of La and Ce exhibit high magnetic properties of Hcj = 8.2 kOe and (BH)max= 10.3 MGOe at room temperature. MM substitution also significantly strengthens the temperature stability of coercivity. The coercivities of the samples with x = 0.2 and even 0.4 exhibit large values close to that of Nd13.5Fe79.5B7 ribbons above 400 K. [ABSTRACT FROM AUTHOR]

The hard magnetic MMCo5 nanoflakes with high coercivity and narrow size distribution have been successfully obtained by three steps surfactant-assisted ball milling (SABM). The magnetic properties, phase structure and morphology of these MMCo5 nanoflakes were studied in this work. The coercivity and the remanence ratio of MMCo5 nanoflakes reached to 5.89 kOe and 0.75, respectively. The X-ray powder diffraction (XRD) patterns indicated that the MMCo5 nanoflakes were CaCu5-type hexagonal crystal structure. The average thickness, in-plane size and aspect ratio reached to 20 nm, 0.9 μm and 60, respectively. The low cost and great properties of MMCo5 nanoflakes with a centralized thickness distribution could be the building blocks for the future high-performance nanocomposite permanent magnets with an enhanced energy product. [ABSTRACT FROM AUTHOR]

The effects of different direct chilling casting speed and mischmetal (i.e.，Ce and La elements) addition on microstructure and mechanical properties of Al-23% Si were investigated. The results showed that when the casting speed increases from 100mm/min to 250mm/min， the segregation of primary Si is restricted effectively， the distribution of primary Si becomes more uniform in different positions of the ingot， the size of primary Si is greatly decreased from 71.4μm to 40.9μm and the segregation of eutectic Si is also reduced. With an addition of 0.5% mischmetal， the size of eutectic Si refines and its morphology changes from flake-like shape to short rod-like one. Both hardness and tensile strength increase with the increase of DC casting speed and the addition of mischmetal. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The influence of various alloying elements (i.e., Sn, Al, Si, Mm, Sc) with different quantities on the microstructure and mechanical properties of gravity die cast magnesium alloys are investigated. Experimental evidences show that the secondary dendrite arm spacing is increasing with the increase in Sn content from 5% to 8% in Magnesium alloy. Misch Metal (Mm) addition in Mg-5%Sn causes grain refinement (∼30%) and the shape of interdendritic second phase particles changes from rod/irregular geometry to feathery shape. In Mg-8%Sn-3%Al-1%Si alloy, α-Mg, Mg 2 Sn, Mg 17 Al 12 and Mg 2 Si phases are identified. Addition of Al-Sc master alloy refines the grain size (∼12%) of Mg-8%Sn alloy. Solution heat treatment at 520 °C for 48–72 h leads to complete dissolution of Mg 2 Sn intermetallic for Mg-Sn alloys. During ageing of Mg-Sn alloys at 200 °C, discontinuous precipitation of Mg 2 Sn occurs at grain boundaries and their triple junctions at the initial stage and later they become coarse in nature. Tensile properties (i.e., YS, UTS and %EL) are improved after 100 h of aging for all alloys used compared with the cast alloys of same composition. Cast Mg-8%Sn-3%Al-1%Si alloy exhibits superior tensile properties as compared to cast Mg-5%Sn, Mg-8%Sn,Mg-5%Sn-2%Mm,Mg-8%Sn-3%(Al-Sc) alloys. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

For this work, hot-rolled plates of medium carbon steel (0.5%C) were prepared with different sulphur contents (0.023% to 0.065%). Two steels were alloyed with mischmetal (0.01%) as inclusions modifier to evaluate its effect on fatigue and tensile properties. A detailed study of the type, size, shape and distribution of the sulphide inclusions was carried out by optical and SEM microscopy in the as-cast and hot rolled conditions and correlated with their mechanical properties. The mischmetal treated steels developed a globular, small (~2µm) and well distributed MnS inclusions, producing an improvement in tensile strength (840 MPa and 19% elongation) and fatigue behavior (375 MPa), which was not evident on the untreated steels (741 MPa tensile strength and 300 MPa fatigue limit). The fatigue behavior was tested under the E466 standard, by using nine samples per composition in a R.R. Moore – rotating beam fatigue testing machine. The higher fatigue limit was obtained for the mischmetal-treated steel with 0.05%S. These results were discussed and correlated to the small size and globular shape of the MnS inclusions. However, it was observed that, additions of 0.01% of mischmetal are less effective as inclusion modifier when sulphur content is higher than of 0.05%, but it is still good enough to obtain a better fatigue behavior compared with the untreated steel containing 0.023% sulphur.