Effect Of Ce Addition Research Articles

The Effect of Ce Addition on the Creep Resistant Mg-Sr-Mn Alloys

Recent studies on Mg-Sr-Mn system exhibited the importance of α-Mn dynamic precipitation during creep on creep strengthening. In the present work, the effect of trace levels of Ce addition on the creep resistance of Mg-Sr-Mn system was investigated. The creep deformation in the quaternary alloys (Mg-Sr-Mn-Ce) were four times lower than the deformation seen in ternary alloys (Mg-Sr-Mn). Dynamic co-precipitation of Mg12Ce and α-Mn was mainly responsible for creep strengthening. Additionally, the presence of a trace amount of Sr in the Mg matrix affected the growth of the creep-induced Mg12Ce precipitates which were found to be lying parallel to the []Mg direction. This growth orientation is different from the orientation of Mg12Ce precipitates typically observed in Mg-Ce binary and Mg-Ce-Mn ternary alloys where plate-like precipitates lie along []Mg.

Effect of Ce Addition on Microstructure and Mechanical Properties of ZM21 Magnesium Alloys

In this paper, the effects of Ce addition on the microstructure and mechanical properties of the cast and extruded ZM21 magnesium alloy were investigated by OM, XRD, SEM and tensile test at room temperature. It was found that with increase of Ce content, the Mg-Ce and Mg-Zn phases which gather in dendritic gap as second phases increase gradually, and form a network structure finally, which becomes thicker due to serious segregation. Meanwhile, Most of Ce in the extruded ZM21 magnesium alloy is in the forms of second phases, and is broken and dispersed in the matrix alloy during the plastic deformation. With the increase of Ce content, the quantity of the second phase increases, and both the tensile strength and the elongation of ZM21 alloys decrease firstly and then increase. When the content of Ce is 0.57%, the elongation barely reaches the level of ZM21 magnesium alloy. After extrusion, both the tensile and yield strength have been greatly improved.

Effect of Ce on morphology of α(Al)–Al2Cu eutectic in Al–Si–Cu alloy

The effect of Ce addition on the morphology of the α(Al)–Al2Cu eutectic in Al–Si–Cu alloy was investigated using thermal analysis, light microscopy, scanning electron microscopy, focused ion beam and energy dispersive analysis. The results show that the eutectic α(Al)–Al2Cu forms within small space between dendrites, silicon and AlSiFeMn plates. Eutectic Al2Cu is not lamellar but degenerated. However, Al2Cu in Ce-modified alloys is more compact. Ce partially dissolves in Al2Cu, which is a viable reason for the formation of coarser Al2Cu. The addition of Ce also increases the microhardness of the α(Al)–Al2Cu eutectic by almost 10% compared with the basic Al–Si–Cu alloy.

Effect of Ce addition on microstructure of Mg–9Li alloy

The as-cast and as-extruded Mg–9Li, Mg–9Li–0.3Ce alloys were respectively prepared through a simple alloying process and hot extrusion. The microstructures of these alloys were investigated by optical microscope (OM), scanning electron microscope (SEM), X-ray diffractometer (XRD) and energy dispersive spectrometer (EDS). The results indicate that Ce addition produces a strong grain refining effect in Mg–9Li alloy. The grain size of the as-extruded alloy reduces abruptly from 88.2 μm to 10.5 μm when the addition of Ce is 0.36%. Mg12Ce is verified and exists inside the grains or at the grain boundaries, thus possibly pins up grain boundaries and restrains the grain growth.

Effect of Ce addition on Cr/γ-Al2O3 catalysts for methane catalytic combustion

Abstract Cerium modified and chromium-based catalysts using nano-γ-Al 2 O 3 as the carrier were prepared via incipient wetness impregnation method and investigated for the catalytic combustion of methane (CH 4 ). The Cr-based catalysts promoted with 3 wt.% Ce displayed the most effective catalytic activity among all catalysts investigated. In addition, Ce significantly improved the catalytic performance of CH 4 combustion by increasing the amount of reaction site [CrO 4 ] ads species on the surface of Cr-based catalysts. Introduction of Ce content also restrained the deactivation of catalysts at high calcination temperature. Cr-based catalysts modified with cerium seem to be a promising cheap and low-temperature catalyst for CH 4 combustion.

Effect of Ce additions on high temperature properties of Mg–5Sn–3Al–1Zn alloy

The electrochemical behaviour of Mg–xCe–1Zn (x = 3, 8 and 13 wt-%) alloys has been investigated. The alloys were fabricated using a vacuum induction melting method under an argon atmosphere. Potentiodynamic polarisation was carried out in 3·5%NaCl solution of pH 7·2 at room temperature to evaluate the corrosion properties of Mg–xCe–1Zn (x = 3, 8 and 13 wt-%) alloys. The microstructure of the Mg–(3, 8 and 13 wt-%)Ce–1Zn alloys mainly consisted of α-Mg and eutectic Mg12Ce phase. With the increase in Ce contents, the volume per cent and size of the eutectic Mg12Ce phase were increased. Results indicated that the corrosion rate of Mg–xCe–Zn alloy was increased by excessive Ce addition.

Effect of Ce Addition on the Microstructures and Mechanical Properties of a Ni-Co-Based Superalloy

Effects of Ce addition on the microstructures and mechanical properties of the Ni-Co-based superalloy were investigated. The results showed that addition of Ce to the alloys resulted in a Ce-rich phase (Ni,Co)3Ce formation. The rupture life was improved greatly by Ce addition and the optimal Ce addition was about 0.2 wt.%. Both peak stress and critical stress of dynamic recrystallization were increased with increasing (Ni,Co)3Ce phases, which was mainly due to pinning effect on grain boundary sliding by precipitation.

Effect of Ce addition on microstructure of Al20Cu2Mn3 twin phase in an Al–Cu–Mn casting alloy

Abstract Effects of Ce addition on microstructure of Al 20 Cu 2 Mn 3 twin phase and mechanical properties of an Al–Cu–Mn casting alloy were investigated by transmission electron microscopy, selected area electron diffraction, high resolution transmission electron microscopy and tensile test. The results show that rare earth element Ce can retard the formation of the Al 20 Cu 2 Mn 3 phase in the Al–Cu–Mn alloy. Compared with the Ce containing alloy, patterns of particles of the Al 20 Cu 2 Mn 3 phase in the Al–Cu–Mn free Ce alloy are more diverse. The symmetry of neighboring components of twins is characterized by glide reflection and reflection. In addition, twins of the Al 20 Cu 2 Mn 3 phase can enhance the mechanical properties of the Al–Cu–Mn alloy.

Steam reforming of kerosene over a metal-monolithic alumina-supported Ru catalyst: Effect of preparation conditions and electrical-heating test

A plate-type anodic alumina support (γ-Al 2O 3/Fe–Cr–Ni alloy/γ-Al 2O 3) was used to prepare a series of Ru catalysts. The performance of these catalysts was investigated in the steam reforming of kerosene (SRK). Ethanol solution impregnation was used to enhance metal dispersion on the catalyst surface. The catalyst prepared by ethanol solution impregnation and dried at 120 °C (Ru/Al 2O 3-ED) gave a higher metal dispersion and more favorable activity and durability than that prepared in aqueous solution. However, owing to shrinking caused by the oxidation of ruthenium species, high temperature calcination in air after impregnation greatly decreased the metal dispersion on the catalyst surface, regardless of the impregnation solution type. In contrast to calcination in air, high temperature N 2 treatment could decompose the reducible ruthenium species on the Ru/Al 2O 3-ED completely. This indicates that H 2 pre-reduction is not an essential procedure for the SRK reactions over this catalyst. The experimental results also confirm this hypothesis. The effect of Ce addition was also investigated and was found to enhance significantly the catalyst tolerance to carbon deposition thereby improving the SRK durability of Ru/Al 2O 3-ED under a high space velocity. In addition, owing to the high electrical resistance of the Fe–Cr–Ni alloy, the anodic alumina catalyst itself can be used as a heater, when an electrical current is applied along the alloy layer. Under an electrical-heating pattern, the SRK reaction system reached stability within 15 min, offering a strong possibility for shortening the start-up time of conventional reformers from 1 to 2 h to a few minutes.

Improvement of the hydrogen storage properties and electrochemical characteristics of Ti 0.85VFe 0.15 alloy by Ce substitution

The effect of Ce substitution for Ti on the microstructure, hydrogen absorption characteristics and electrochemical properties of Ti 0.85− x Ce x VFe 0.15 ( x = 0, 0.02 and 0.05) is studied in detail. In the Ti–V–Fe series, the composition Ti 0.85VFe 0.15 which crystallizes in single phase BCC structure shows the highest hydrogen storage capacity of 3.7 wt%. In the present study, the effect of Ce addition (2 and 5 at%) on the hydrogen absorption properties of Ti 0.85VFe 0.15 has been investigated by X-ray diffraction, electron probe microanalysis (EPMA) and pressure–composition isotherm studies. The hydrogen absorption capacity is found to be higher for the Ce substituted alloys. The alloys Ti 0.85VFe 0.15, Ti 0.83Ce 0.02VFe 0.15 and Ti 0.80Ce 0.05VFe 0.15 show maximum hydrogen storage capacities of 3.7, 4.02 and 3.92 wt%, respectively. Kinetic studies show that the hydrogen absorption is quite fast for all the three alloys and they reach near saturation value in about 120 s. Electrochemical studies of the Ce (2 at%) substituted alloy, Ti 0.83Ce 0.02VFe 0.15 show higher electrocatalytic activity for the hydrogen electrode reactions as compared to Ce-free parent compound, Ti 0.85VFe 0.15.

Effect of Ce on microstructures and mechanical properties of rapidly solidified Mg–Zn alloy

The rapidly solidified (RS) Mg–Zn based alloys with Ce addition were produced via atomising the alloy melt and subsequent splat quenching on the water cooled copper twin rollers in the form of flakes. The effects of Ce additions on the microstructures, phase compositions, thermal stability and isochronal age hardening behaviour of the RS Mg–Zn alloy were systematically investigated. The RS Mg–6Zn alloy is characterised by fine grains in the size of 6–10 μm and is composed of α-Mg, Mg51Zn20 and a small quantity of MgZn2 and Mg2Zn3 phases. With the increment of Ce, the microstructures of the alloys are refined, and the volume fractions of dispersions are increased remarkably. The stable intermetallic compounds, i.e. the MgxZnyCez ternary phases, are formed in the RS Mg–Zn–Ce alloys at the expense of the Mg51Zn20 phases, which leads to the enhanced thermal stability of the alloys, especially for the Mg–6Zn–5Ce alloy. In the alloy, the atomic percentage ratio of Zn/Ce in the MgxZnyCez phase is close to two, and the maximum hardness is 91·5±7 HV after annealing at 200°C for 1 h. However, the age hardening behaviour of the alloys decreases with the increment of Ce, and the main reason is discussed.

Effect of Ce on solidification and mechanical properties of A360 alloy

The effect of Ce addition on the AA A360 (Al–10%Si–0.5%Mg) alloy was investigated using equilibrium thermodynamic calculation, thermal analysis, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The purpose is to study the variations that occur during solidification and precipitation with different Ce additions, as well as their effect on the mechanical properties. The results show that the Ce addition decreases the eutectic (α Al + Mg 2Si) temperature. The solidus temperature also decreases with the increasing Ce addition. The precipitation enthalpy determined using DSC decreases with the Ce addition, while precipitation takes place more rapidly and intensively, indicating increased reaction kinetics. The mechanical properties like hardness and tensile strength also increase with the Ce addition. The phase that contributed to the hardness of the investigated alloy was composed of Al, Ce, Mg and Si.

Effects of Ce addition on microstructure and mechanical properties of Mg-6Zn-1Mn alloy

The effects of Ce addition on the microstructure of Mg-6Zn-1Mn alloy during casting, homogenization, hot extrusion, T4, T6 and T4+two-step aging were investigated. The mechanical properties of alloys with and without Ce were compared. The results showed that Ce had an obvious effect on the microstructure of ZM61-0.5Ce alloy by restricting the occurrence of dynamic recrystallization and restraining the grain growth during extrusion and heat treatment subsequently. A new binary phase Mg 12Ce was identified in ZM61-0.5Ce alloy, which distributed at grain boundaries and was broken to small particles distributed at grain boundaries along extrusion direction during extrusion. The mechanical properties of as-extruded ZM61-0.5Ce alloy were improved with the addition of Ce. The improved tensile properties of as-extruded ZM61-0.5Ce alloy were due to the finer grain sizes as compared to ZM61 alloy. However, the UTS and YS decreased severely and the elongation increased when ZM61-0.5Ce was treated by T6 and T4+two-step aging. Brittle Mg 12Ce phase, which was distributed at the grain boundary areas and cannot dissolve into the Mg matrix after solution treatment, became crack source under tensile stress.

Effect of Ce addition on the oxidation behaviour of Mo–Si–B–Al ultrafine composites at 1100 °C

Mo 73.4 Si 11.2 B 8.1 Al 7.3 ultrafine eutectic–dendrite composites undergo severe oxidation at 1100 °C in dry air, being transformed completely into mullite and cristobalite. However, the net mass loss is reduced by at least ∼ 40 % during 24 h exposure upon minor Ce addition to the alloy, indicating an unusual improvement in oxidation resistance. The presence of Ce hinders mullatization, and leads to the formation of a protective Si–O-rich layer in the scale. The relationship between oxide scale composition and the oxidation kinetics has been examined.

Influence of rare earth on the microstructure and age hardening response of indirect-extruded Mg-5Sn-4Zn alloy

The effects of Ce addition on the microstructure, age hardening response and mechanical properties of an indirect-extruded Mg-5wt.%Sn-4Zn (TZ54) alloy were investigated. Addition of Ce accelerated the aging response with the peak aging time moving from 300 h in TZ54 to 30 h in Mg-5wt.%Sn-4Zn-1Ce (TZE541), while the peak harness was similar to each other. The addition of Ce also caused an increase in the precipitation stability during overageing. Though the tensile strength of extruded TZ54 was improved by the addition of Ce, the tensile strength of the TZE541 was reduced after T6-treatment. The combined mechanical properties of the present as-extruded alloys by solution heat-treatment and artificial aging (T6) were comparable to commercial wrought magnesium alloys.

Effects of Ce Addition on the Microstructure and Mechanical Properties of Sn-58Bi Solder Joints

The effects of a rare-earth element on the microstructure, mechanical properties, and whisker growth of Sn-58Bi alloys and solder joints in ball grid array (BGA) packages with Ag/Cu pads have been investigated. Mechanical testing indicated that the elongation of Sn-58Bi alloys doped with Ce increased significantly, and the tensile strength decreased slightly, in compar- ison with undoped Sn-58Bi. In addition, the growth of both fiber- and hillock-shaped tin whiskers on the surface of Sn-58Bi-0.5Ce was retarded in the case of Sn-3Ag-0.5Cu-0.5Ce alloys. The growth of interfacial intermetallic compounds (IMC) in Sn-58Bi-0.5Ce solder joints was slower than that in Sn-58Bi because the activity of Ce atoms at the interface of the Cu6Sn5 IMC/solder was reduced. The reflowed Sn-58Bi and Sn-58Bi-0.5Ce BGA packages with Ag/Cu pads had a ball shear strength of 7.91 N and 7.64 N, which decreased to about 7.13 N and 6.87 N after aging at 100°C for 1000 h, respectively. The reflowed and aged solder joints fractured across the solder balls with ductile characteristics after ball shear tests.

Effects of Ce Addition on the Mobility and Hot Tearing Tendency of Al-4.5Cu Alloy

This paper aims to study the effects of rare earth Cerium addition on mobility, solidification shrinkage, casting microstructure and hot tearing tendency of Al-4.5Cu alloy. Results show that by adding appropriate rare earth Cerium into the Al-4.5Cu alloy, the viscosity of liquid metals can be reduced, the mobility of alloy can be increased, and the shrinkage during the solidification of liquid metal can be reduced. Further more, as the tendency of alloy dendrite is inhibited and the microstructure of the casting alloy is improved, the alloy can be purified, its thermal conductivity can be enhanced, and the hot tearing tendency of it can be decreased remarkably. It proves that when rare earth Ceriumaddition in Al-4.5Cu alloy is 4w%, the mobility of Al-4.5Cu alloy will be the maximum, and its volume shrinkage will be the least. Meanwhile, the grains of alloy are refined and round. The alloy also shows the lowest hot tearing tendency.

Effect of Ce addition on macroscopic core-shell structure of Cu–Sn–Bi immiscible alloy

To investigate the evolution of bimetallic composite structure of immiscible alloy, a macroscopic core-shell type structure of 24Cu–16Sn–60Bi alloy was fabricated which consisted of (Cu 3Sn, Cu 10Sn 3) central core and Bi periphery. Ce addition was found to be capable of enhancing remarkably Marangoni motion of secondary droplets in liquid matrix. The role of Ce addition was attributed to change interfacial tension of droplet/matrix. The results show the possibility of modulating core-shell type structure in immiscible materials by doping rare earth elements.

Influence of Co or Ce addition on the NO x storage and sulfur-resistance performance of the lean-burn NO x trap catalyst Pt/K/TiO 2-ZrO 2

The Pt/K/TiO 2-ZrO 2 catalysts promoted by Co or Ce were prepared by successive impregnation or mechanically mixing method. The influence of Co or Ce addition on the NO x storage and sulfur-resistance performance of the catalyst was investigated carefully. The techniques of XRD, FT-IR, in-situ DRIFTS, H 2-TPR and XPS were employed for catalyst characterization. The Co or Ce addition can greatly improve the NO x storage capacity of Pt/K/TiO 2-ZrO 2 due to the enhanced oxidation ability and the release of more K sites. Ce addition induces higher K/Ti atomic ratio and larger NO x storage capacity as compared with Co addition. After sulfation and regeneration, the promoted catalysts shows more or less decreased NSC than Pt/K/TiO 2-ZrO 2 due to the formation of more sulfates, especially for the Co-promoted catalysts, which possess better oxidation ability and facilitate the formation of large sulfates. The effect of Ce addition on Pt/K/TiO 2-ZrO 2 largely depends on the addition mode. The high oxidation ability and the high K/Ti ratio of the mechanically prepared Ce-promoted catalyst make it still possess considerable NO x storage capacity (NSC) of 142 μmol/g after sulfation and regeneration. With the decrease of sulfur content in fuels, the Co- and Ce-promoted catalysts possessing large NO x storage capacity, will be applicable to the purification of lean-burn NO x.

Effect of Ce addition on the microstructure and damping properties of Cu–Al–Mn shape memory alloys

The effect of rare earth element Ce addition on the microstructure, martensitic transformation, mechanical properties and damping behavior of the Cu–Al–Mn shape memory alloys (SMAs) had been investigated. It is shown that the Ce addition makes the grain refinement and affects the martensitic transformation temperature. The tensile strength and the ductility of the Cu–Al–Mn alloys can be enhanced by the Ce addition. Damping capacity tan δ of the martensite for the Cu–Al–Mn–Ce alloys is strain amplitude dependent. The Ce addition has obvious effects on the damping properties of the martensite. With the increase of the Ce content, the damping capacity increases initially and then decreases.