Effect Of Ce Addition Research Articles

Effect of CE Addition on Microstructure, Thermal and Mechanical Properties of Al-Si Alloys

Effect of CE Addition on Microstructure, Thermal and Mechanical Properties of Al-Si Alloys

Effect of CE Addition on Microstructure, Thermal and Mechanical Properties of Al-Si Alloys

Effect of CE Addition on Microstructure, Thermal and Mechanical Properties of Al-Si Alloys

Effect of Ce addition on hot deformation behavior and microstructure evolution of AZ80 magnesium alloy

Hot compression tests of AZ80 and AZ80-Ce alloys were conducted on a Gleeble-3800 simulator at strain rates of 0.01–10 s−1 and deformation temperatures of 340–420 °C. The effects of Ce addition on hot deformation behavior and microstructure evolution of AZ80 magnesium alloys were investigated. The rare earth phase formed with added Ce hindered movement of the dislocations and grain boundaries, causing higher peak stress of AZ80-Ce alloy than that of AZ80 alloy. Existing large-size Al4Ce particles as second phase in AZ80-Ce alloy increased the driving force of recrystallization, promoting dynamic recrystallization and reducing dislocation density. After hot compression, AZ80 alloy showed a fiber texture with the c-axis parallel to the compression direction, and addition of Ce caused texture-weakening. The constitutive equations and processing maps of AZ80 and AZ80-Ce alloys were constructed and analyzed. Adding Ce reduced deformation activation energy and Zener-Hollomon parameter, and enlarged non-instability zone in processing maps of AZ80 alloy.

Effects of Ce Addition on Solidification Structure of a Low-Carbon 42CrMo4 Steel

Effects of Cerium (Ce) addition on solidification structure of a low-carbon 42CrMo4 steel was investigated. The addition of up to 0.067 wt.% of Ce in the steel produced greatly improved solidification structure with a suppressed columnar grain zone, finer grain size in an equiaxed grain zone and zero area fraction of casting shrinkage cavity. The added Ce occurred in the steel both in the form of Ce oxy-sulfide inclusions and as dissolved atomic Ce segregated together with other elements at prior austenite grain boundaries and at interdendritic spacing. The Ce oxy-sulfide inclusions were found to play a major role in the observed improved grain structure meanwhile dissolved Ce had pronounced effects on morphology of dendritic networks. The fraction of Ce dissolved in the melt appeared to bring about increase in fluidity of the molten steel, leading to total elimination of interdendritic shrinkage porosity in solidification structure of the steel with added Ce. Ce addition can be considered as a potential solution for grain structure refinement in heavy-weight castings of 42CrMo4 steel grade.

Influence of Ce Addition on Microstructure and Corrosion Resistance of 2101 Duplex Stainless Steel

2101 duplex stainless steel with low Ni content is developed to replace austenitic stainless steel in many corrosive environments. Herein, the effects of Ce addition on the microstructure and corrosion resistance of 2101 duplex stainless steel are studied. The electrochemical corrosion behavior of 2101 duplex stainless steel with Ce contents of 0, 0.005, and 0.020 wt% is studied in 3.5 wt% NaCl solution and 0.05 mol L−1 H2SO4 + 0.05 mol L−1 KSCN solution at 25 °C. The situation is evaluated in 6 wt% FeCl3 solution at 35 °C. The results show that with increasing Ce content, the proportion of α phase in 2101 duplex stainless steel decreases, whereas the proportion of γ phase increases. At 0.005 wt% Ce, the two‐phase ratio is close to 1:1. Moreover, the partition coefficient (K) of elements gradually approaches 1 with increasing Ce, indicating a more uniform element distribution between the two phases. The electrochemical experiments in simulated seawater and acidic environments show that Ce addition gradually increases the corrosion potential and pitting resistance, leading to the formation of more stable passivation film.

Effect of Ce Addition on Inclusions and Grain Structure in Gear Steel 20CrNiMo

Through laboratory experiments and thermodynamic calculation, the chemical composition and morphology of inclusion and grain size in the cast melt are comprehensively characterized herein. The results show the evolution of Al2O3 inclusion formed by Al deoxidation in the gear steel 20CrNiMo follows the route of Al2O3 → CeAlO3 → Ce2O2S → Ce2O2S + CeS, and thus the nucleation core of complex CemnS sulfides changes from CeAlO inclusion to CeOS inclusion with the increase in Ce addition. Moreover, grain size of gear steel 20CrNiMo treated by Ce addition decreases from 491.4 to 164.0 μm, because both the Ce2O2S and CeS form with Ce addition and have potential to be effective heterogeneous nucleation agents for the primary δ‐ferrite during the solidification process of gear steel 20CrNiMo. And statistical results show that the percentage of small inclusion with a diameter less than 3 μm are, respectively, 64.4%, 86.5%, 96.4%, 93.6%, and 75.6% in the steel samples with Ce content of 0, 13, 31, 77, and 203 ppm. Thus, the recommended Ce content to achieve fine inclusions and solidification structure of gear steel 20CrNiMo is 31 ppm.

Effects of Ce Addition on Mechanical and Corrosion Properties of the As-Extruded Mg-Zn-Ca Alloy

The microstructure and corrosion properties of the as-extruded Mg-Zn-Ca alloy with and without Ce addition are investigated. The microstructure was characterized by optical microscopy, scanning electron microscopy coupled with electron backscatter diffraction detector. Ce addition retarded dynamic recrystallization during deformation, which resulted in the formation of bimodal microstructure with finely dynamically recrystallized (DRXed) grains and coarsely unDRXed grains. Texture of the DRXed region was weakened after small addition of Ce, mainly attributing to particle stimulated nucleation. The strength enhancement for the Ce containing Mg-Zn-Ca alloy was attributed to the fine microstructure and strong texture. Corrosion results indicated that Ce addition deteriorated corrosion resistance in 3.5 wt.% NaCl solution of the as-extruded Mg-Zn-Ca alloy, which was related to the dispersed second phases, refined microstructure and weak basal texture in DRXed region.

Characteristics on microstructure and mechanical performances of 6111Al influenced by Ce-containing precipitates

In this work, the effects of Ce addition (0, 0.1 wt%, 0.3 wt%, 0.5 wt% and 0.7 wt%) on the evolution of microstructure and mechanical properties of 6111Al alloy and strengthening mechanism of 6111Al–Ce alloy were systematically investigated by a polarizing microscope, a scanning electronic microscope, an energy dispersive spectroscope and a high-resolution transmission electron microscope. The results indicate that with 0.3 wt% Ce addition, the α-Al grains show the equiaxed crystal morphology with the average size decreasing from 137 to 57 μm and numerous small AlCeSi phases with lump-like or plate-like morphology are distributed closely along the grain boundary. The peak yield strength, ultimate tensile strength and elongation of 6111Al–Ce alloy reach to 279 MPa, 316 MPa and 12.1%, respectively, which is attributed to the grain refinement strengthening and the formation of nanosized Al11Ce3 precipitates. Eventually, this investigation gives us instructive suggestion to prepare the new kind of aluminum alloy with high strength and high ductility.

Effects of cerium addition on the corrosion resistance and biocompatibility of Mg–2Sr–1Zr Alloy

Abstract

Effect of Ce Addition and Heat Treatment on Microstructure Evolution and Tensile Properties of Industrial A357 Cast Alloy

The effects of adding different Ce contents (0–0.32 wt.%) on the microstructure, mechanical properties, and fracture morphology of industrial A357 cast alloy in as-cast and T6 heat treatment were studied. The main purpose of this study is to improve the microstructure stability and tensile properties of industrial A357 cast alloy. The microstructural analyses indicate that the addition of Ce causes refinement of the α-Al primary phase for the reason that the formation of intermetallic compounds containing (AlSiCeMg) elements enriches the front of the solid–liquid interface, which causes an increase in constitutional undercooling. Simultaneously, the addition of Ce also affected the characteristics of eutectic Si particles, which make its morphology change from acicular structures into fragmented and spheroidized. This is mainly due to the formation of Ce-rich precipitates during solidification, which increase the constitutional undercooling and suppress the nucleation of the eutectic Si particles, resulting in the change of eutectic Si characteristics. Moreover, the needle-like morphology of a Fe-containing intermetallic is transformed into α(AlSiFeCe) phase containing rare earth Ce when part of the Ce atoms entered β(Al5FeSi) phase compounds. The tensile properties of the modified alloys were improved in the as-cast and T6 heat treatment as a consequence of simultaneous refinement of both secondary dendrite arm spacing and grains and the improvement of eutectic Si particles and Fe-containing intermetallic morphology. The fracture surface of the modified alloy has more dimples than the unmodified alloy, which indicates that the main fracture pattern of the modified alloy is dimple fracture caused by the crack of eutectic Si particles. The optimal percentage of Ce in industrial A357 cast alloy was determined to be 0.16 wt.% according to the change of microstructures structure and mechanical properties. These experimental results provide a new basis for adding rare earth Ce to improve the performance of parts in the actual production of industrial A357 cast alloy.

Effect of Ce Addition on the Tribological Behavior of ZK60 Mg-Alloy

The present work aims to study the tribological behavior of an extruded ZK60 alloy in the presence of Ce; in a previous study, among ZK60 alloys with different Ce addition rates, an alloy with 3 wt% of Ce was found to exhibit the most promising mechanical (e.g., hardness and strengths) properties, while its wear behavior remained unknown. The results of microstructural examinations by optical and electron microscopes show that Ce addition reduces the grain size from 6.1 to 2.0 μm. Besides, in addition to the precipitates already distributed in the base alloy (Mg7Zn3), Ce could promote the formation of a new precipitate (MgZn2Ce), increasing the total fraction of the precipitates. These microstructural evolutions enhance the strengths of the studied ZK60 alloy, as the yield and tensile strengths increase from 212 to 308 MPa and from 297 to 354 MPa, respectively. A pin on disc tribometer was employed to study the wear behavior of the developed alloy under different normal loads (5, 20, 40, and 60 N). The results show that the base and Ce-added alloys exhibit almost a similar frictional behavior, while the wear resistance of the Ce-added alloy is higher within the load ranges applied: (i) in low load conditions (5 and 20 N), where the abrasive wear is the active mechanism, the precipitates in the Ce-added alloy could enhance the wear resistance. (ii) Under the load of 40 N, oxidative wear is also an operative wear mechanism, leading to a sharp increase in the wear rate of the alloys. In this condition, Ce could provide a protective oxide layer, which could improve the wear resistance of the alloy. (iii) At a load of 60 N, both studied alloys exhibit a similar wear rate due to a severe oxidation condition. Therefore, beyond this loading condition, the microstructural evolutions (e.g., change in precipitation behavior) caused by Ce addition can no longer contribute to the enhancement of wear resistance.Graphic

Improving strength and corrosion resistance of high Mg alloyed Al–Mg–Mn alloys through Ce addition

ABSTRACT Micro-alloying is thought to improve the performance of Al–Mg alloys commonly used in transport applications. The effect of Ce addition (not higher than 0.9 wt-%) on the microstructure, corrosion behavior, and mechanical properties of the Al–9.2Mg–0.7Mn alloy was systematically investigated to assess its potential use in engineering applications. Ce addition had a significant effect on pitting corrosion resistance due to its segregation in the Mn-rich phase. In particular, the pitting corrosion rate of the alloy in the sensitization state decreased substantially with Ce addition, and was approximately 48 and 53% lower than that of the alloy matrix with 0.1 and 0.3 wt.% Ce, respectively. In addition, its strength was improved through 0.3 wt.% Ce addition (providing an increase in ultimate tensile strength of approximately 30 MPa) at no expense to intergranular corrosion resistance, indicating that Ce micro-alloying could comprehensively improve the properties of Al–Mg–Mn alloys.

Effect of Ce addition on microstructure, mechanical properties and corrosion behavior of Al-Cu-Mn-Mg-Fe alloy

The effects of rare earth Ce on the microstructure, mechanical properties and corrosion behavior of Al-Cu-Mn-Mg-Fe alloys were investigated by means of microstructure analysis, tensile test and electrochemical corrosion test. The research shows that the Al-Cu-Mn-Mg-Fe alloy after low temperature heat treatment mainly contains the S (Al2CuMg) phase, the T (Al20Cu2Mn3) phase, the Al6 (Mn, Fe) phase and the Al7Cu2Fe phase, and the rare earth Ce makes the alloy form the new rare earth phase Al8Cu4Ce. The appearance of this phase has a significant refinement effect on the Al6 (Mn, Fe) phase. Compared with Ce-free, the yield strength and tensile strength of Al-Cu-Mn-Mg-Fe alloy with 0.254 ωt% Ce increased by 7% and 15%, respectively, and the elongation increased from 3.1% to 4.8%. It also has better corrosion resistance, which is represented by the decrease of corrosion current density and positive shift of corrosion potential in Tafel measurement in solutions of different concentrations, and the increase of corrosion impedance in electrochemical impedance spectroscopy test, especially the corrosion current density was reduced by 6.06 μA cm−2 in 3.5% NaCl solution.

Effect of Ce addition on microstructure evolution and precipitation in Cu-Co-Si-Ti alloy during hot deformation

Abstract Hot compression behavior of the Cu–Co–Si and Cu–Co–Si–Ti alloys was studied using the Gleeble-1500 simulator at 0.001–10 s−1 strain rate and 500–900 °C deformation temperature. Ti addition increased the flow stress of the Cu–Co–Si–Ti alloy compared with the Cu–Co–Si alloy at the same deformation conditions. With the deformation temperature increased from 700 °C to 900 °C, the Cu–Co–Si alloy texture transformed from the copper texture to the R texture. Due to the addition of Ti, the copper texture and R texture were substituted by the Goss texture and the copper texture, respectively. The constitutive models of the Cu–Co–Si and Cu–Co–Si–Ti alloys hot deformation behavior were obtained. The activation energy of the Cu–Co–Si alloy was 411.648 kJ/mol, and the activation energy of the Cu–Co–Si–Ti alloy was 500.794 kJ/mol, which is 27% higher. The precipitated Co2Si phase was found in both Cu–Co–Si and Cu–Co–Si–Ti alloys deformed at 700 °C and 0.001 s−1. In addition, the CoSi and Cu4Ti phases were found in the Cu–Co–Si and Cu–Co–Si–Ti alloys, respectively. The strengthening mechanisms, including dispersion strengthening, twinning and grain refinement strengthening, control the Cu–Co–Si–Ti alloy hot deformation, and lead to increased flow stress and activation energy, and inhibit dynamic recrystallization of the Cu–Co–Si–Ti alloy.

Effect of Ce addition on mechanical properties and shape memory effect of Cu-14%Al-4.5%Ni shape memory alloy

Abstract This investigation examines the influences of the (Ce) addition on the mechanical properties and the shape memory effect (SME) of the Cu-based shape memory alloys (SMAs), in which (Ce) is added in three percentages (0.3, 1.0 and 3 wt%) to the base material (Cu-14%Al-4.5%Ni). Different tests and inspections, including X-ray diffraction, compression, HV hardness, and the thermomechanical tests were conducted on the (Ce-modified) alloys. In addition, a differential scanning calorimetry test, microstructure examination via optical measurements, and (SEM) for the whole alloys were performed. Results revealed an increment in the hardness, the yield strength and the maximum strain (e max%) occurred with the increase of the (Ce %) in the base shape memory alloy (with exception of the 3% Ce case). The thermomechanical characteristics depicted an increment in the recovery of strain by as much (98.72%) with a reduction in the modulus of elasticity of martensite and an increment in the modulus of elasticity of austenite. Moreover, the temperatures of transformation shifted to beyond the base shape memory alloy domain (100–170 °C), and the modified (SMA) with (3% Ce) exhibited better results than the other materials.

Effect of Ce Addition on Fluidity of Casting Aluminum Alloy A356

Fluidity is an important factor defining the castability of aluminum casting alloys. In this study, the influence of Ce addition on the fluidity of A356 alloy was investigated using a multichannel fluidity test mold. There is a non-monotonic relationship between fluidity length and Ce content. Addition of Ce below 0.3 wt pct was shown to increase the fluidity of A356 alloy. The fluidity length of the alloy with 0.3 wt pct Ce improved from 93.2 to 130.2 mm compared with that of A356 alloy due to the refinement of α-Al and the modification of eutectic Si. The addition of Ce could provide nucleation particles and cause constitutional undercooling in A356 alloy. Furthermore, the addition of Ce decreased the eutectic temperature and induced twinning of Si. However, with a higher Ce content, the fluidity length dramatically decreased because of the formation of intermetallic compounds. When the content of Ce is 0.5 wt pct, a mass of reticular Al-20Si-10Mg-3Fe-Ce intermetallic compounds was found in the melt. When the Ce content further increased to 0.7 wt pct, the fluidity worsened (73.3 mm). Excess Ce element reacts with Ti in the alloy to form the Al-17Ce-12Ti-2Si phase, resulting in the formation of coarse primary dendrites of α-Al, which would damage the fluidity of A356 alloy.

Effect of Ce Addition on the As-Cast and As-Forged Microstructure of Fe-TiB2 Composites

The effects of Ce addition on the as-cast and as-forged microstructure of Fe-TiB2 composites were explored. Fe-TiB2 composites with hypereutectic concentration were formed in situ from Fe-Ti-B melts at various cooling rates with the addition of the rare-earth element Ce. The size of both primary and eutectic TiB2 particles increased with a decrease in the cooling rate. Many clustered primary particles were found in the Ce-free specimens, while the addition of Ce significantly refined the TiB2 particles and scattered them into a dispersed distribution. Hot forging tends to further refine the size and enhance the number density of eutectic TiB2 particles. A decrease in interparticle spacing could be achieved by an increase of cooling rate, the addition of Ce, or hot forging. Tensile strength and hardness of the Fe-TiB2 composites both increased with decreasing interparticle spacing in accordance with the Hall–Petch relationship. Engineering strain was enhanced by Ce addition, then further improved by hot forging, and the proportion of dimpled region in the fracture surface was improved as well. Ce addition and hot forging enhanced both the tensile strength and the ductility of Fe-TiB2 composites.

Effect of Ce addition on hot tearing behavior of AZ91 alloy

A small amount of cerium (below 1.0 wt%) addition to AZ91 alloy have been investigated on the hot tearing susceptibility (HTS) at a cooling rate of 1.5Ks−1. The HTS increased to a maximum value with a cerium addition of 0.6 wt% and then decreased to a stable status as cerium was gradually added. Due to high chemical activity, cerium into the melts can react with aluminum to form an Al11Ce3 intermetallic compound. X–ray diffraction results also confirmed the existence of Al11Ce3. The Al11Ce3 increased with the presence of the needle-like and block morphology. As cerium levels increased, the amount of Mg17Al12 decreased. The variations between Mg17Al12 and Al11Ce3 resulted in a similar normal distribution of the HTS in AZ91 alloy. The findings were further verified through the microstructure evolution and the surface morphology of fracture.

The effect of Ce addition (up to 3%) and extrusion ratio on the microstructure and tensile properties of ZK60 Mg alloy

In this study, attempts have been made to investigate the effects of both Ce addition and Extrusion Ratio (ER) on the microstructure and tensile properties of ZK60 alloy. With this aim, different amounts (1, 2 and 3 wt%) of Ce were added to a based ZK60 alloy and then the investigated alloys experienced the hot extrusion process with different ERs (12:1 and 18:1). It was found out that Ce addition could refine the cast (non-deformed) microstructure as the finest grain size (35 μm) was obtained in Ce-containing (3 wt%) alloy. Besides, the results of XRD demonstrated that, in addition to Mg7Zn3 that already existed in the base alloy, a new precipitate (MgZn2Ce) would form in the presence of Ce. This led to an increase in fraction of the precipitates with Ce addition. Microstructural observations showed that applying the extrusion process on the cast alloys, especially with higher ER, would significantly refine the size of grains and precipitates. The grain refinement might be due to the microstructural evolutions taken place during exerting the extrusion forces as well as the dynamic recrystallization. It was found out that Ce addition in both cast and deformed conditions could enhance the hardness and strength of the alloys, while it would have no or negative effect on their elongation. Compared to the cast condition, extruded alloys exhibited far better mechanical properties, especially when higher ER (18:1) has been employed; as the highest hardness (88 HV), yield (308 MPa) and tensile strengths (354 MPa) have been obtained in 3 wt% Ce-containing alloy extruded with ER of 18:1. However, higher ER resulted in lower elongation of the studied alloys.

Effects of Ce Addition on Grain Boundary Character Distribution, Corrosion Behavior and Impact Toughness of AISI 204Cu Stainless Steel

In this study, the effects of Ce addition on grain boundary character distribution, corrosion behavior and impact toughness of AISI 204Cu stainless steel were investigated. The results revealed that rare earth Ce affected the characteristics and size of inclusions, and the change in the austenite grain size was attributable to Ce multi-phase inclusions as the core of heterogeneous nucleation in stainless steel. The high adjacent probability of γ-fiber textures comprising {111} 〈110〉 and {111} 〈112〉 components was available for more ∑3n boundaries with increasing Ce contents, which was believed to have a contribution to the enhancement of corrosion resistance. Meanwhile, the austenite grain refinement and ∑3n boundaries increment were beneficial for the impact toughness improvement of Ce-added steel by increasing the difficulty of crack initiation and propagation. Adding excessive Ce caused a decline in the corrosion behavior and impact toughness of 204Cu stainless steel.