Addition Of Sm Research Articles

The Role of Sm in Precipitates, Grain Sizes,and Tensile Properties of As‐Cast and As‐Extruded AZ31–0.3La Alloys

Herein, the effect of Sm on precipitates, grain sizes, and tensile properties of AZ31–0.3La alloy is investigated. Results indicate that Sm is almost dissolved in α‐Mg matrix with 0.2% content, whereas Al2Sm with two kinds of morphologies forms with further Sm addition. The grain sizes of as‐cast studied alloy increase first and then decrease with increasing Sm addition, whereas the dynamic recrystallization (DRX) grain sizes decrease first and then increase, and the DRX grain size distribution is uniform first and then uneven. During the hot extrusion process, the refinement of DRXed grains is attributed to the particle‐stimulated nucleation (PSN) mechanism. The Rp0.2 (yield strength) of as‐extruded studied alloy is changed from twin‐dominated to slip‐dominated by 0.2% Sm addition, and the basal texture is slightly weakened due to the refined DRX grains and even‐distributed grain size distribution, and the minor solute Sm atoms segregating at grain boundaries. Finally, the Rp0.2 of the as‐extruded AZ31–0.3La alloy is gradually enhanced with increasing Sm addition, and the A (elongation) is increased to 25% with 0.2% Sm addition and maintains to about 20% with 0.6–1.7% Sm addition.

Effect of samarium and praseodymium addition on water gas shift performance of Co/CeO2 catalysts

The performance of Co supported over ceria and doped ceria (by Sm and Pr) catalysts towards the water gas shift reaction was studied for the removal of CO from syngas to produce high purity hydrogen for a fuel cell application. It is found that 1%Co/Ce-5%Sm-O yields the highest catalytic performance towards this reaction compared with undoped-Sm and doped-Pr. An addition of Sm onto ceria support reveals a small crystallite size with high surface area and well dispersed cobalt on ceria surface. Moreover, a presence of Sm increases the reducibility of cobalt species and surface oxygen. The positive effect of Sm on increasing the WGS activity of Co/CeO2 is because Sm contributes to the reduction of Ce4+ to Ce3+ which gives rise to oxygen vacancies and facilitates the electron movement at the surface leading to an ease of surface reduction.

Ferroelectric, dielectric, and impedance properties of Sm-modified Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 ceramics

To investigate the effect of Sm doping on the electrical properties of Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 (BZT-xBCT) (x = 40, 50, 60) ceramics, three Sm-modified ceramics were prepared using the conventional solid-state reaction method. Related electrical measurements, including ferroelectric and dielectric investigations and impedance spectroscopy, were recorded for these ceramics. It was found that a tilted morphotropic phase boundary resulted from the addition of Sm, which induced the best piezoelectric properties and insulating behaviour in the Sm-BZT-60BCT sample. An abnormal P-E loop shrinkage appeared in the Sm-BZT-50BCT sample but not in the other two samples. This could be attributable to the different electronegativities between Ca2+ and Ba2+ and between Zr4+ and Ti4+, whose contents are different in varied samples and have an effect on defect-dipole alignment as well as spontaneous polarization. The activation energies for the bulk conductivity in the three composites were calculated to be 0.28 ± 0.01, 0.08 ± 0.01, and 0.36 ± 0.01 eV, confirming the existence of oxygen vacancies in our samples. The Sm dopant is responsible for the oxygen vacancies. This also leads to an increased Curie temperature in the three composites.

The effect of Sm addition on structure, redox properties and catalytic activities for water gas shift reaction of ceria-based support

Oxygen vacancy in ceria-based support is a dominate factor for catalyzing the water gas shift reaction by faster a redox cycle between Ce4+ and Ce3+ which is one of the elementary step in WGS reaction mechanism. Therefore, in this work, CeO2-based support was incorporation by Sm ion in order to produce the oxygen vacancy defect site. Ce1-xSmxO2 (x = 0.010, 0.050, and 0.10 at%) mixed oxide supports were synthesized by urea gelation to investigate the role of Sm addition into ceria-based support on surface, structural and redox properties which was altered to their catalytic activities. XRD and Raman spectroscopy results indicated the incorporation of Sm3+ into CeO2 lattice which gave rise to unit cell enlargement and led to structural distortions inside CeO2 which produced strain and unbalanced charge and then finally facilitated oxygen vacancy formation. XANES and EXAFS results also evidenced the replacement of Sm3+ into Ce4+ site in CeO2 lattice. H2-Temperature programmed reduction and temperature-resolved X-ray absorption spectroscopy (under reduction condition) were employed to investigate the reducibility of Ce1-xSmxO2 supports. XANES spectra of Ce L3 edges displayed lower surface reduction temperature (Ce4+ to Ce3+) which corresponded to H2-TPR results. The results of catalytic activity tests for water gas shift reaction showed that the activity of 1 wt%Pd/Ce1-xSmxO2 was higher than that of 1 wt%Pd/CeO2. The role of Sm on enhancing WGS reaction rate were to increase CO molecules adsorption by promoting the dispersion of active metal site on catalyst surface and to facilitate the redox cycle between Ce4+ and Ce3+ of ceria support by oxygen vacancies formation. Therefore, combined these two effects the WGS activities were enhanced. Moreover, by using the results from our previous works together with the results from this work, we can evidence that speeding up the different elementary steps in the reaction mechanism, the WGS rate can also be enhanced.

Effect of addition of small amounts of samarium on microstructural evolution and mechanical properties enhancement of an as-extruded ZK60 magnesium alloy sheet

The microstructure, texture evolution and mechanical properties of as-extruded Mg-5.5Zn-0.8Zr (wt.%) (ZK60) alloy with 1 % Sm addition were investigated. The results showed that the as-extruded ZK60-1Sm alloy consisted of α-Mg, Mg2Zn3, Mg7Zn3, Mg41Sm5 and (Mg, Zn)3Sm phases. The addition of 1 %Sm precipitated the Mg41Sm5 and (Mg, Zn)3Sm phases, which promoted the dynamic recrystallization (DRX) in the subsequent extrusion process and resulted in grain refinement. The microtexture and the orientation distribution characteristic implied that large amounts of <01–10> and <-12–10> slips were activated in ZK60-1Sm alloy during extrusion process, while only <01–10> basal slip was observed in ZK60 alloy. The non-basal slips led to more potential nucleation sites and a better coordination for the deformation, resulting in the better comprehensive mechanical properties of the as-extruded ZK60-1Sm sheet. Meanwhile, the as-extruded ZK60-1Sm alloy showed higher strength and ductility compared to ZK60 alloy. The ultimate tensile strength (UTS), the yield strength (YS) and the elongation to failure (EL) along the extrusion direction (ED) were enhanced by 11.7 %, 24.5 % and 26.2 %, respectively. The influence of fine grain microstructure, nanoscale Mg41Sm5 phase, micron scale (Mg, Zn)3Sm phase and texture evolution, contributed mainly to the strength of as-extruded ZK60-1Sm alloy.

Influence of Sm on the low temperature NH3-SCR of NO activity and H2O/SO2 resistance over the SmaMnNi2Ti7Ox (a = 0.1, 0.2, 0.3, 0.4) catalysts

A series of Sm-modified SmaMnNi2Ti7Ox (a = 0.1, 0.2, 0.3, 0.4) catalysts were synthesized and showed better NH3-SCR activity than MnNi2Ti7Ox, meanwhile, the Sm0.3MnNi2Ti7Ox sample exhibited much higher low temperature NH3-SCR performance below about 200 °C, and good SO2 and/or H2O durability. The bulk and surface physicochemical properties were measured to investigate the influence of the Sm addition on the activity by various characterization methods including NO/NH3 oxidation, NH3-TPD, H2-TPR, XRD, N2 adsorption-desorption, XPS. The results illustrate that the Sm addition can not only increase the adsorbed NO/NH3 species, BET surface area, surface acid amount, Mn4+ content, surface adsorbed oxygen and the redox ability but also inhibit the generation of ammonium sulfate/bisulfate, which are beneficial to the NH3-SCR activity. Moreover, the in situ diffuse reflectance infrared Fourier transform spectroscopy was applied to analyze the reaction process, which reveals that the NH3-SCR reaction follows both E–R and L-H mechanisms over Sm0.3MnNi2Ti7Ox.

Study of Al-Zn-Cu-Sm Efficiency for Low-Voltage Sacrificial Anode Candidate

Sacrificial anode is one of the most effective methods for preventing corrosion in seawater environment. Aluminum (Al) anode works very well in seawater environment with high electrochemical capacity and high driving voltage. Commonly used aluminum alloy sacrificial anodes have the possibilities to trigger the occurrence of Stress Corrosion Cracking and Hydrogen Embrittlement due to overprotection on high-strength steel. The low voltage sacrificial anode was developed to overcome this problem. Electrochemical behavior of Al-5Zn-0.5Cu alloy with varied samarium (Sm) addition of 0.02 wt% and 0.1 wt% was investigated in this study. The commonly used Al-5Zn-0.02In alloy is also tested as a comparison. Anode efficiency test with weight loss method according to DNVGL-RP-B401 standard was conducted to determine the performance of Al-5Zn-0.5Cu-xSm alloy. The addition of 0.1 wt% Samarium shows the best anode performance with electrochemical capacity 2809.80 Ah/kg and 98% efficiency. Al-5Zn-0.5Cu-0.1Sm alloy is the most potential alloy to be developed as a low potential sacrificial anode to replace commonly used aluminum sacrificial anode with indium addition.

Effect of Sm on Crystallization Kinetics of Cu-Zr-Al Metallic Glasses

The effect of Sm micro-alloying on non-isothermal and isothermal crystallization kinetics of (Zr50Cu40Al10)100-xSmx (x = 0, 2, 4 at. % Sm) alloys were investigated using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Crystallization activation energies for each composition were calculated in non-isothermal conditions using Kissinger and Ozawa methods and in isothermal conditions using Johnson-Mehl-Avrami model. XRD analysis showed that crystallization product Cu10Zr7 changes to Cu2Sm with Sm presence in isothermal conditions. Both isothermal and isochronal calculations yield that the energy barrier for crystallization has increased with Sm addition. On the other hand, crystallization point drops to lower temperature at the expense of an increase in the pre-exponential factor. The Avrami exponents for all compositions were found to be below 2.5, indicating that crystallization was governed by a diffusion-controlled three-dimensional growth with a decreasing nucleation rate. The apparent increase in crystallization activation energies with increasing Sm content can be one of the affecting factors for commonly held idea of increased glass forming ability for rare-earth containing Zr-based metallic glasses.

Doping and adsorption mechanism of modifying the eutectic Mg2Si phase in magnesium alloys with rare earth elements: A first-principles study

Modification mechanism of the rare earth elements (RE = La, Ce, Nd and Sm) on the eutectic Mg2Si phases investigated by experiments and theoretical calculations in this work. Experimental results indicate that La has the best modification effect on eutectic Mg2Si. The properties of RE atoms doping and adsorption on Mg2Si(1 0 0) and (1 1 1) surfaces were calculated by first-principles calculation method. Results show that Nd atom exhibit the greatest doping effect on Mg2Si(1 0 0), whereas La atom is most likely to dope on (1 1 1) surface rather than (1 0 0) surface. RE atoms are prefer to be adsorbed at vacancy site on (1 0 0) surface and H2 site on (1 1 1) surface. And the adsorption energies of both vacancy and H2 sites are in the order of La < Ce < Nd < Sm. Both theoretical and experimental results suggest that adsorption should be the primary reason of modifying the eutectic Mg2Si phase in magnesium alloy with addition of RE elements La, Ce Nd and Sm. And the best modification effect on eutectic Mg2Si phase can be achieved with the addition of La element.

Microstructure and mechanical properties of AZ91 magnesium alloy with minor additions of Sm, Si and Ca elements

The effects of Sm, Si and Ca on the microstructure and mechanical property of AZ91 magnesium alloy were investigated by means of optical microscopy (OM), differential scanning calorimetry (DSC), scanning electronic microscopy (SEM), X-ray diffraction (XRD) and tensile testing. The results indicated that the addition of 1.5 wt.% Sm with or without 0.8 Si/Ca led to a decrease in the volume fraction of the β-Mg17Al12 phase and the formation of the intermetallic compounds of Al-Sm, Mg2Si, MgAlCa and Al2Ca. The microstructure of AZ91 alloy was significantly refined and distribution became discrete with additions of Sm and Ca; the average grain size of the α-Mg matrix was reduced from 239.7 ± 16.9 µm to 66.34 ± 5.10 µm. The AZ91-Sm-Ca alloy exhibited a good combination of yield strength at 135 MPa, ultimate tensile strength at 199 MPa and elongation at 4.32%, which was ascribed to grain refinement strengthening. Furthermore, the T6 treated AZ91-Sm-Ca alloy possessed yield strength of 154 MPa and elongation of 7.1%, which was due to grain refinement strengthening and reduction in discontinuous precipitates.

Grain-refinement strengthening effect of Y and Sm on magnesium alloy AZ81

The grain refinement mechanism and resulting grain-refinement strengthening effect of rare earth elements Y and Sm on magnesium alloy AZ81 have been investigated by means of microstructure analysis, tensile tests and theoretic calculation. The results show that the formation of high melting-point Al2Y and Al2Sm phases is observed in magnesium alloy AZ81 after 1.8 wt% Y and Sm addition. The phases act as the heterogeneous nucleation cores of α-Mg matrix, and refine the grain size. It leads to the effective grain-refinement strengthening and enhance the strength of the alloy.

PHYSICOCHEMICAL, MICROSTRUCTURAL AND SENSORY IMPACT OF FAT REPLACERS ON LOW-FAT EDAM CHEESE MANUFACTURED FROM BUFFALO’S MILK

The objective of the current work was to evaluate the effect of three different commercial protein-based fat replacers Prolo®11(PR), Simplesse®100 (SM) and Dairy LoTM (DL) on the physicochemical, microstructural, and sensory characteristics of low-fat Edam cheese (LFEC) made from buffalo’s milk during a specific ripening period. LFEC treatments were prepared using different ratios (0.3%, 0.6%, and 0.9% w/w marked I, II and III respectively) for each PR, SM and DL. Cheese without fat replacer was prepared as the control (C). Cheese containing fat replacers had a higher significant moisture content than C. Proteolysis significantly increased in LFEC containing Fat replacers more than C. Firmness decreased gradually with increasing the concentration of the fat replacers. PRIII and SMIII had less firmness. The addition of SM and PR improved texture, flavour and acceptability of the LFEC on the 60th day of ripening. DL treatments achieved the best total scores for sensory characteristics on the 90th day of ripening. Fat replacers affected the microstructure of LFEC especially SM which imparts a desirable texture to cheese, compared to other treatments.

Effects of Sm on Microstructure of Mg-12Gd-2Y-0.5Zr Alloy

By alloy melting, microstructure analysis and micro-hardness test, the effects of Sm addition on the microstructure of Mg-12Gd-2Y-0.5Zr alloy with solution treatment and aging treatment were investigated. The results showed that the microstructure of the tested alloy consisted of α-Mg matrix, Mg41Sm5, Mg5Gdm, Mg24Y5 and β’ phases, and Sm improved the micro-hardness value of α-Mg matrix attributed to its better solid solution strengthening effect in α-Mg. The micro-hardness of the alloy with Sm increases obviously from HV121.4 to HV134.3 when compared with that of Mg-12Gd-2Y-0.5Zr alloy.

Microstructure and mechanical properties of Mg-Gd-Y-Sm-Al alloy and analysis of grain refinement and strengthening mechanism

The effects of Sm on the microstructure and mechanical properties of Mg-11Gd-2Y-0.6Al alloy were investigated by X-ray diffraction, optical microscopy, scanning electron microscopy, energy dispersive spectrometry and high resolution transmission electron microscopy. Based on the theory of edge–edge matching and electronegativity theory, the mechanism of grain refinement is discussed. The strengthening mechanism is expounded conveniently from fine grain strengthening, coherent strengthening, precipitation strengthening and grain boundary strengthening. The results show that the microstructure of Mg-11Gd-2Y-0.6Al alloy is mainly composed of α-Mg matrix, Mg5Gd and Mg24Y5 phases. The addition of Sm forms Mg41Sm5 phase in the alloy and refines the alloy. The addition of Sm significantly improves the mechanical properties of the alloy at room and high temperatures. When the addition of Sm is 3 wt%, the tensile strengths of the alloy at room temperature and high temperature (200 °C) reach the maximum value 292 and 321 MPa, respectively. The fracture mode of the alloy at different temperatures is mainly brittle fracture and intercrystalline fracture.

Generalized Stacking Fault Energy of {10-11} Slip System in Mg-Based Binary Alloys: A First Principles Study.

In this work, the generalized stacking fault energies (GSFEs) of {10-11}<11-23> slip system in a wide range of Mg-X (X = Ag, Al, Bi, Ca, Dy, Er, Gd, Ho, Li, Lu, Mn, Nd, Pb, Sc, Sm, Sn, Y, Yb, Zn and Zr) binary alloys has been studied. The doping concentration in the doping plane and the Mg-X system is 12.5 at.% and 1.79 at.%, respectively. Two slip modes (slip mode I and II) were considered. For pure magnesium, these two slip modes are equivalent to each other. However, substituting a solute atom into the magnesium matrix will cause different effects on these two slip modes. Based on the calculated GSFEs, two design maps were constructed to predict solute effects on the behavior of the {10-11}<11-23> dislocations. The design maps suggest that the addition of Ag, Al, Ca, Dy, Er, Gd, Ho, Lu, Nd, Sm, Y, Yb and Zn could facilitate the {10-11}<11-23> dislocations.

Investigations on microstructures, mechanical and corrosion properties of Mg-5.5Zn-0.8Zr alloys with Sm addition

The microstructure, mechanical and corrosion properties of as-cast Mg-5.5Zn-0.8Zr (ZK60) alloys with varying Sm contents were investigated. The microstructures of the ZK60 alloy mainly consisted of α-Mg grains and Mg7Zn3 particles in common. Addition of Sm to ZK60 alloy resulted in the formation of Mg41Sm5 and (Mg, Zn)3Sm phases, which changed the number, morphology and distribution of the second phase of the alloy, resulting in finer, more homogeneous grains and improved mechanical properties. The ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) of the ZK60-0.8Sm alloy were increased by 19.8%, 25.3% and 31.7%, compared to those of ZK60 alloy, from 162 to 194 MPa, 74.4 to 93.2 MPa and from 6.0% to 7.9%, respectively. The corrosion mode of Sm-containing ZK60 alloys changed from serious local corrosion to uniform corrosion, and the corrosion resistance was improved. When the content of Sm was 1.6 wt%, the corrosion rate of the alloy was 1.7102 g · cm−2 · h−1, which was only 89% of the corrosion rate of ZK60 alloy. The improvement of the properties of ZK60-xSm alloys was attributed mainly to the interaction of solid solution strengthening, fine grain strengthening and precipitation strengthening.

Dependence of structural cross-linking, system energy and transition temperature on coordination number for Sm doped GST

Abstract Ge2Sb2Te5 is one of the prominent phase change memory material for non-volatile data storage due to high crystallization temperature and fast crystallization speed. The physical correlations have been employed to narrate the structural alteration of Ge2Sb2Te5 on Sm incorporation. The calculation of structural change has been performed by calculating the change in net constraints (Ncon) with mean coordination (Z) on Sm addition. There is an increase in fraction of zero frequency modes (Mf) and cross-linking density (DCL) on Sm incorporation. The structural cross-linking shows a three dimensional network formation. There is an enhancement in density and compactness on Sm addition. The degree of covalency (>93%) shows a decrease in ordering and leading to an increase in glass formation tendency. The calculated values of band gap show an increase on Sm addition which is in good agreement with increase in cohesive energy calculated using chemical bond approach (CBA). Using CBA, the glass transition temperature has been estimated and is correlated with the increase in cross-linking in the system.

Effect of Sm on Microstructure, Mechanical Property and Lattice Constant of As-Cast Mg–11Gd–2Y–0.6Al Alloy

Mg–11Gd–2Y–xSm–0.6Al (x = 0, 1, 3, 5) alloys were prepared in electromagnetic induction furnace by gas protection. The crystal structure, microstructure and mechanical properties of as-cast Mg–11Gd–2Y–xSm–0.6Al alloys were studied by X-ray diffraction, metallographic microscope, scanning electron microscopy and tensile testing. The results show that the main phases of Mg–11Gd–2Y–xSm–0.6Al alloys are α-Mg matrix, Mg5Gd, Mg24Y5 and Mg41Sm5. The addition of Sm refines the microstructure and increases the number of second phase in the grain boundary. The diffraction peaks of the cylindrical plane (100)α-Mg, base plane (002)α-Mg and conical plane (101)α-Mg are shifted to a low angle. The offset of diffraction peak and the lattice constant of α-Mg increase with the increase in Sm content. The crystal axis ratio decreases with the increase in Sm content. When the addition of Sm is 3%, the ultimate tensile strength reaches to 240 MPa, which increases by 17.07%. The improvement in mechanical properties is mainly attributed to the grain refinement and the decrease in the crystal axis ratio of α-Mg.

Structure, magnetic and ferroelectric properties of Sm and Sc doped BiFeO3 polycrystalline ceramics

The polycrystalline Bi1-xSmxFe0.97Sc0.03O3 (x = 0.08, 0.12) ceramics have been synthesized using a modified solid-state reaction method. The Bi0.92Sm0.08Fe0.97Sc0.03O3 ceramic possesses single polar rhombohedral R3c phase, while a polar rhombohedral R3c and an anti-polar orthorhombic Pbam phases coexist in the Bi0.88Sm0.12Fe0.97Sc0.03O3 ceramic. The density and the grain uniformity of all the doped ceramics get improved. Further, the addition of Sm and Sc has resulted in significant improvement in ferroelectric characteristics. In addition to this, it also releases the latent magnetization by suppressing the spiral spin structure. The well-defined polarization along the field direction is confirmed by the saturated hysteresis phase loops from 180° domains by piezoresponse force microscopy. The anti-polar Pbam phase experiences a visually electric field induced phase transition to polar R3c phase in the Bi0.88Sm0.12Fe0.97Sc0.03O3 ceramic.

Effects of samarium content on microstructure and mechanical properties of Mg–0.5Zn–0.5Zr alloy

Effects of samarium (Sm) content (0, 2.0, 3.5, 5.0, 6.5 wt%) on microstructure and mechanical properties of Mg–0.5Zn–0.5 Zr alloy under as-cast and as-extruded states were thoroughly investigated. Results indicate that grains of the as-cast alloys are gradually refined as Sm content increases. The dominant intermetallic phase changes from Mg3Sm to Mg41Sm5 till Sm content exceeds 5.0 wt%. The dynamically precipitated intermetallic phase during hot-extrusion in all Sm-containing alloys is Mg3Sm. The intermetallic particles induced by Sm addition could act as heterogeneous nucleation sites for dynamic recrystallization during hot extrusion. They promoted dynamic recrystallization via the particle stimulated nucleation mechanism, and resulted in weakening the basal texture in the as-extruded alloys. Sm addition can significantly enhance the strength of the as-extruded Mg–0.5Zn–0.5 Zr alloy at room temperature, with the optimal dosage of 3.5 wt%. The optimal yield strength (YS) and ultimate tensile strength (UTS) are 368 MPa and 383 MPa, which were enhanced by approximately 23.1% and 20.8% compared with the Sm-free alloy, respectively. Based on microstructural analysis, the dominant strengthening mechanisms are revealed to be grain boundary strengthening and dispersion strengthening.