Effect Of Fe Addition Research Articles

Effects of Fe addition on the mechanical and corrosive properties of biomedical Co-Cr-W-Ni alloys for balloon-expandable stents

Co-20Cr-15W-10Ni (mass%, CCWN) alloy is extensively used as a platform material for balloon-expandable stents. In this study, the mechanical properties of CCWN alloy are improved following the addition of Fe, and the effects of Fe addition on the mechanical and corrosive properties of the alloy are investigated. As-cast specimens were fabricated by adding pure Fe to a commercially available CCWN alloy (base alloy) such that the resulting alloys contained 4, 6, and 8 mass% Fe. The as-cast specimens were subjected to homogenization heat treatment at 1523 K for 7.2 ks and then hot-forged at 1473 K (as-forged specimens). The as-forged specimens were cold-rolled at a reduction rate of 30% and heat-treated at 1473 K for 300 s (recrystallized specimens). The matrix of the recrystallized base- and Fe-containing alloys consisted of a single γ (face-centered cubic)-phase. The Fe-added alloys revealed precipitates composed of the η-phase (M6X-M12X-type phase, M: metallic element, X: C and/or N). The average grain size of the recrystallized base and Fe-added alloy specimens was approximately 34 μm and the amount of added Fe had no significant effect on the static recrystallization behavior of the resulting alloys. Alloys containing 6 mass% or more Fe showed improvements in strength and ductility compared with the base alloy. When the Fe-added alloys were compared, their strength decreased whereas their ductility increased when the added Fe increased. Because Fe acts as a γ-phase-stabilizing element for Co, Fe addition increases the stacking fault energy of the base alloy, resulting in the formation of the ε (hexagonal close-packed)-phase owing to the suppression of strain-induced martensitic transformation (SIMT), and improvements in ductility. No deterioration in corrosion resistance was observed following the addition of up to 8 mass% Fe to the base alloy. Based on these results, the addition of Fe to CCWN alloy may be considered an effective method to improve its mechanical properties, especially ductility, without impairing its corrosion resistance. The results of this study will be useful for the future development of Ni-free Co-Cr alloys for next-generation, small-diameter stents.

Effect of Fe addition on corrosion behavior of Ni–xFe–5Cr alloys at 570°C in air containing salt vapor

Effect of Fe addition on corrosion behavior of Ni–<i>x</i>Fe–5Cr alloys at 570°C in air containing salt vapor

Effect of Fe Composition and Heat Treatment Temperature on the Transformation Temperature of R-Phase of Ti-Ni-Fe Alloy

R-phase transformations in TiNi shape memory alloys (Nitinol) have various applications because of their small thermal hysteresis and low fatigue resistance. Adding a third element such as Fe or Al is one of the useful ways to induce R-phase transformation. Controlling the R-phase transformation temperature is crucial for industrial and bio-field applications. However, the effects of adding Fe have rarely been reported. In this study, the effects of Fe addition and heat treatment temperature on the R-phase transformation temperature of TiNiFe shape memory alloys were systematically investigated. Results showed that increasing Fe composition decreases the R-phase and martensitic transformation temperatures of 19K/1at%Fe and 51 K/1at%Fe, respectively. Additionally, in the Ti–49Ni–1Fe alloy, rather than a martensite transformation, the R phase transformation temperature was constant irrespective of heat treatment temperature and increasing number of thermal cycles. This means that the R-phase transformation temperature is not affected by dislocation density resulting from the heat cycling or cold working processes. This allows practical applications of R-phase transformation to be easily realized. Furthermore, this means that the R-phase transformation temperature is only affected by the Ni content of the matrix.

The effect of Fe addition on high temperature transformations of specific silica sources

The effect of Fe addition on high temperature transformations of specific silica sources

Effect of Fe addition on phase evolution, microstructure and properties of Ti50Ni50-X Fe X alloy

The work aims to study the effect of the Fe content on the properties of Ti50 Ni(50−X) Fe X alloy (where X = 0, 2, 4, 6, 8, and 10 at.-%) sintered at 1050°C and 1150°C using the conventional sintering technique. The microstructure, chemical composition and phase evolution of the sample were analysed by SEM, EDS, and XRD, respectively, along with various properties. It was observed that the sintered sample microstructure consists of (Ni, Fe)-rich, and Ti-rich phases. Here, the porosity decreases, whereas density, hardness, and wear resistance increase with the increasing temperature. The 8at.-%Fe sample shows lower porosity and higher wear resistance, relative density and hardness value than other Fe content samples. The 2at.-%Fe sample sintered at 1050°C shows a higher shape recovery value compared to other compositions sintered at various temperatures.

Fabrication of nickel-titanium-iron shape memory alloys by powder metallurgy route and analyses of their physical and mechanical behaviour

ABSTRACT In this research work, the effect of Fe additions on the phase evolution, microstructure, chemical composition, transformation behaviour and properties of Ni(50−X)Ti50FeX shape memory alloys has been investigated. The elemental Ti, Ni and Fe mixed powders are compacted at 600 MPa, followed by sintering at 1100°C for 4hr in an Ar atmosphere. Phase analysis and microstructural studies confirmed the presence of the NiTi phase besides other Ni-rich and Ti-rich phases. The 8at.-% Fe sample shows higher relative density, lower porosity, higher hardness, higher elastic modulus and higher wear resistance owing to the presence of a higher amount of secondary intermetallic phases compared to other composition samples. Interestingly, the 4at.-% Fe sample has a higher percentage of NiTi (B19’) phase and shows a better shape memory effect and elastic recovery than other composition samples. FESEM morphology of worn surface explained various wear mechanisms with respect to shape memory behaviour.

Effect of Fe additions on microstructure and mechanical properties in near-eutectic Al–Ce alloys

The effects of adding 1 or 3 wt % Fe to a near-eutectic Al–10Ce alloy are investigated in terms of their as-cast and aged microstructures, thermal stability, and creep resistance. A 1 wt% Fe addition forms fine, Chinese-script Al10CeFe2 and Al11Ce3 eutectic phases without loss of microhardness as compared to the Fe-free Al–10Ce alloy, unlike in traditional cast Al-alloys where detrimental coarse phases are observed when adding Fe. Adding 3 wt% Fe increases hardness significantly while forming primary Al10CeFe2 in a coarse rod morphology. These near-eutectic Al–10Ce–1Fe and hyper-eutectic Al–10Ce–3Fe alloys, after thermal exposure at 400 and 425 °C for up to 384 h, show only a small loss in microhardness, indicating excellent coarsening resistance. Compressive creep measurements performed at 300 °C show similar trends: (i) near-eutectic Al–10Ce–1Fe performs quite similarly to near-eutectic Al–10Ce and (ii) hyper-eutectic Al–10Ce–3Fe exhibits much improved creep resistance, similar to near-eutectic Al–10Ce–5Ni with costly Ni additions, and much better than hyper-eutectic Al–13Ce. After surface laser remelting to simulate laser powder-bed fusion, the near-eutectic Al–10Ce–1 Fe alloy exhibits greatly refined Al10CeFe2 and Al11Ce3 eutectic phases with a doubling in microhardness, indicating a strong potential for laser-based additive manufacturing. Cast Al–Ce–Fe-based alloys show great promise as low-cost alloys with high creep- and coarsening-resistance for use at high temperatures, with the high Fe tolerance enabling the use of recycled aluminum with high Fe contamination.

The Effect of Fe Addition on the Curie Temperature and Magnetic Entropy of the Gd45Co50Al5 Amorphous Alloy.

The new magnetic refrigeration (MR) technology, which uses the magnetocaloric effect (MCE) of materials for refrigeration, has shown apparent advantages over the compression refrigeration of freon and other gases. Therefore, how to obtain materials with excellent magnetic entropy change near room temperature is of great significance for the realization of MR. In order to achieve high Tc of a Gd-based amorphous alloy, Gd45Co50Al5 amorphous alloy with good room temperature MCE was selected, and a series of Gd45Co50-xFexAl5 (x = 2, 5, 10) amorphous alloys were prepared by adding Fe instead of Co. In this paper, the effect of Fe addition on the Curie temperature, and the magnetic entropy change in the alloys, were studied thoroughly. The results show that the Curie temperature is increased to 281 K by adding 5% Fe elements, which is mainly related to the enhanced 3d-3d interaction of transition elements caused by Fe addition, and the maximum value of magnetic entropy change is 3.24 J/(kg·K) under a field of 5 T. The results are expected to provide guidance for further improving the room temperature MCE of Gd-based amorphous alloys.

Effects of Fe-Addition as a Beneficial Modifying Element on the Microstructure and Mechanical Properties of an Al–Si–Cu–Mg–Ni–Mn Piston Alloy

Effects of Fe-Addition as a Beneficial Modifying Element on the Microstructure and Mechanical Properties of an Al–Si–Cu–Mg–Ni–Mn Piston Alloy

Effect of Fe Addition on Anaerobic Digestion Process in Treating Vinasse: Experimental and Kinetic Studies

Vinasse is a continuously resulting waste by a bioethanol industry with a high chemical oxygen demand (COD) concentration and a large volume. Anaerobic digestion (AD) is the best method to treat vinasse because it converts COD to biogas, so the biogas can support the Indonesia's primary energy need. The goal of this study was to study the effect of Fe concentration on the AD process in treating the vinasse. The Fe concentration was varied to 0.06, 0.29, 0.64, 0.99 g/L. The results showed that increasing the Fe concentration from 0.06 to 0.29 g/L intensified the biogas yield by 360% (from 10.8 to 49.6 mL/g COD). However, further increasing the Fe concentration to 0.99 g/L decreased the biogas yield by 37.8% (from 10.8 to 6.7 mL/g COD). The Fe significantly affected the methane formation stage, but not the acid formation stage. A mechanistic model was built and successfully applied to predict the AD process. Based on the simulation results, Fe concentration of 0.29 g/L resulted in the highest values of YVFA/X2 (yield of volatile fatty acids (VFAs) consumption per biomass of X2 ), μm,2 (specific growth rate for X2 ), fCH4 (composition of methane in biogas) and the lowest values of Ks,VFA (affinity coefficient in VFAs consumption), kd2 (death rate constant for X2 ), kVFA (consumption rate of VFAs for maintenance). The addition of Fe until 0.29 g/L was recommended to increase the quantity and quality (methane content reached 53.4%) of biogas production.

Effects of Fe addition on pyrolysis characteristics of lignin, cellulose and hemicellulose

In this paper, the pyrolyzed influence of Fe contents (0%, 1% and 5%) on the lignin, cellulose and hemicellulose were carried out by thermogravimetric and Fourier transform infrared spectroscopy. The pyrolysis process, kinetic characteristics and release characteristics of the pyrolysis products on the three major components were studied. The results showed that the addition of Fe increases the yield of cellulose biochar. The yield of lignin and hemicellulose biochar are also related to the addition of Fe. The kinetic analysis showed that Fe supplementation significantly decreases the activation energy of lignin, but increases the activation energy of cellulose, while the activation energy of hemicellulose was closely related to Fe addition (149.95 kJ/mol under 1% Fe and 127.84 kJ/mol under 5% Fe). The release characteristics of the pyrolysis products showed that the observed pyrolysis products mainly included H2O, CH4, CO2 and CO. An addition of 5% Fe increased CH4, CO and CO2 production in the pyrolysis process of the three components and produced less H2O.

Action and segregation mechanism of Fe-rich phase in as-cast brass with different Fe contents

Rational recycling of scrap brass is an important link in the global copper supply chain. It is of great significance to clarify the mechanism and tolerance of trace elements in scrap brass. Fe is one of the main trace elements that commonly found in scrap brass. In this study, the effect of Fe on the properties (conductivity and hardness) of brass as cast was investigated in the range of iron content from 0 to 1.2 wt%. The effect of Fe addition on the action and the corresponding segregation mechanism of Fe-rich phase in as-cast brass was reported in this paper. The thermodynamic model of Fe segregation in brass was established. Based on the theoretical analysis, the mechanism of Fe segregation in brass was revealed. This work contributes to a new understanding for the separation behavior of Fe-containing particles in Cu-rich melt. These results may provide theoretical guidance for reasonable regeneration and utilization of scrap brass.

Strip Casting of Al-4.7%Mg with Impurity Fe Using a Single Roll Caster with a Scraper

Fe was added to Al-4.7%Mg to make model alloys of recycled Al-Mg alloy. The effect of Fe addition on the mechanical properties of the Al-4.7%Mg strip cast using a single-roll caster equipped with a scraper was investigated. The added Fe content was 0.2, 0.4, 0.6, and 0.8%. The as-cast strip cast at 30 m/min was cold rolled down to a thickness of 1 mm thick annealed to conduct a tensile test and a cup test. The as-cast strip could be cold rolled without cracking. The tensile stress and the 0.2% proof stress were only slightly affected by the addition of Fe. The elongation gradually decreased as the Fe content increased. When the Fe content was 0.8%, the elongation in the casting direction was 27.7%. The limiting drawing ratio did not deteriorate until the Fe content was 0.4%. When the Fe content was 0.4% and 0.8%, the limiting drawing ratios were 2.0 and 1.7, respectively.

High strength and rapid solution Mg alloy by adding Fe element fabricated by binder jetting additive manufacturing

The effects of Fe addition on the mechanical properties and corrosion behaviors of AZ91D alloys prepared by binder jetting additive manufacturing have been investigated. The results show that the constitution of the second phase is large dependence on Fe content. With the Fe content increasing, the second phase can transform AlFe phase to Fe and AlFe phase. In addition, with increasing Fe content, the content of second phase increases gradually, while the content of pores also increases. We believe that with the Fe content increasing, the content of second phase with Fe element increases which the melt temperature is higher than sintering temperature, and the content of liquid phase decreases, that leading the high-viscosity liquid alloy cannot fill the pores fully and the more pores will remain and causes the relative density reduces. The compressive strength shows a parabola relationship with Fe content. Furthermore, adding Fe can accelerate the degradation of Mg alloys owing to the galvanic corrosion. The sample with 5 wt% Fe content shows the highest ultimate compressive strength (440 MPa) and fast degradation rate (9091 mm/Y), which meets the soluble Mg alloy with rare earth but cost much lower.

Effect of Fe addition on the microstructure, transformation behaviour and superelasticity of NiTi alloys fabricated by laser powder bed fusion

ABSTRACT NiTi-Fe ternary shape memory alloys were produced by laser powder bed fusion (L-PBF) using the pre-alloyed NiTi and elemental Fe powders. A large process window exists to fabricate dense NiTiFe0.3 and NiTiFe0.5 alloys, while severe cracks occur in the NiTiFe2 alloy. The cracking susceptibility is studied through thermodynamic analysis. Fe is mainly dissolved in the NiTi matrix, which is mainly due to the low Fe addition and rapid cooling associated with L-PBF process. The martensite transformation temperatures (MTTs) decrease monotonously with the increase of scanning speed, the decrease of laser power, or the increase of Fe addition, providing a feasible approach to tailoring the MTTs. Due to the decrease of the MTTs, the NiTiFe0.3 and NiTiFe0.5 alloys show good superelasticity, e.g. the NiTiFe0.3 alloy shows a superelastic recoverable strain of 5.2% (pre-strain of 6%). This work suggests that L-PBF is a potential method to in-situ synthesise ternary NiTiFe alloys.

Effect of Fe addition on the glass-forming ability, stability, and mechanical properties of Zr50Cu34-xFexAl8Ag8 metallic glasses

Zr50Cu34-xFexAl8Ag8 (x = 0, 2, 4, 6, and 8) alloy bars of different diameters were prepared by copper mold suction casting and copper mold casting. The compressive mechanical properties of metallic glass samples with different Fe contents were determined by a universal testing machine. The microstructure and thermodynamics of the alloy samples were analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry. According to the experimental results, Fe doping had a significant effect on the glass-forming ability, stability, and mechanical properties of these metallic glasses. The maximum diameter of the Zr50Cu32Fe2Al8Ag8 metallic glass bar was 15 mm, and the cooling rate of the alloy sample was 7.7 K/s. The addition of Fe inhibited the formation of stable crystalline phases inside the alloy sample and improved the glass-forming ability of the metallic glass. With the addition of Fe, the DSC curve of the alloy sample moved to higher temperatures, and the characteristic temperatures and the stability of the metallic glass increased. The fracture strength (σmax) and ultimate strain (εf) of the metallic glass samples reached their maximum values of 1917.6 MPa and 3.97 %, respectively, for Zr50Cu30Fe4Al8Ag8. Compared with the Fe-free Zr50Cu34Al8Ag8 metallic glass, σmax and εf increased by 51.4 MPa and 1.19 %, respectively. With the addition of Fe, the change in the distribution and content of free volume inside the metallic glass sample is the main reason for the improvement of its mechanical properties. This study shows that trace element doping has an important effect on the properties of metallic glasses.

The Effect of Fe Addition in the RM(Nb)IC Alloy Nb-30Ti-10Si-2Al-5Cr-3Fe-5Sn-2Hf (at.%) on Its Microstructure, Complex Concentrated and High Entropy Phases, Pest Oxidation, Strength and Contamination with Oxygen, and a Comparison with Other RM(Nb)ICs, Refractory Complex Concentrated Alloys (RCCAs) and Refractory High Entropy Alloys (RHEAs).

In this work, the RM(Nb)IC alloy Nb–30Ti–10Si–5Cr–5Sn–3Fe–2Al–2Hf (NV2) was studied in the as-cast and heat-treated conditions; its isothermal oxidation at 700, 800 and 900 °C and its room temperature hardness and specific strength were compared with other Sn-containing RM(Nb)ICs—in particular, the alloy Nb–24Ti–18Si–5Cr–5Fe–5Sn (NV5)—and with RCCAs and RHEAs. The addition of Fe (a) stabilised Nbss; A15–Nb3X (X = Al, Si and Sn) and Nb3Si; metastable Nb3Si-m’ and Nb5Si3 silicides; (b) supported the formation of eutectic Nbss + Nb5Si3; (c) suppressed pest oxidation at all three temperatures and (d) stabilised a Cr- and Fe-rich phase instead of a C14–Nb(Cr,Fe)2 Laves phase. Complex concentrated (or compositionally complex) and/or high entropy phases co-existed with “conventional” phases in all conditions and after oxidation at 800 °C. In NV2, the macrosegregation of Si decreased but liquation occurred at T >1200 °C. A solid solution free of Si and rich in Cr and Ti was stable after the heat treatments. The relationships between solutes in the various phases, between solutes and alloy parameters and between alloy hardness or specific strength and the alloy parameters were established (parameters δ, Δχ and VEC). The oxidation of NV2 at 700 °C was better than the other Sn-containing RM(Nb)ICs with/without Fe addition, even better than RM(Nb)IC alloys with lower vol.% Nbss. At 800 °C, the mass change of NV2 was slightly higher than that of NV5, and at 900 °C, both alloys showed scale spallation. At 800 °C, both alloys formed a more or less continuous layer of A15–Nb3X below the oxide scale, but in NV5, this compound was Sn-rich and severely oxidised. At 800 °C, in the diffusion zone (DZ) and the bulk of NV2, Nbss was more severely contaminated with oxygen than Nb5Si3, and the contamination of A15–Nb3X was in-between these phases. The contamination of all three phases was more severe in the DZ. The contamination of all three phases in the bulk of NV5 was more severe compared with NV2. The specific strength of NV2 was comparable with that of RCCAs and RHEAs, and its oxidation at all three temperatures was significantly better than RHEAs and RCCAs.

The effect of Fe addition on γ′ precipitates during thermal exposure in Ni-Co-based single crystal superalloys

The effect of Fe addition on γ′ precipitates in Ni–20Co-xFe-12Cr-7.5Al-7.5Ti-1.5 W (where x = 0 or 4 at.%) single crystal superalloys during thermal exposure process was systematically studied. The results showed that the alloys presented a good microstructure stability and no any harmful TCP phases were formed in the long-term aged microstructures (such as, 1000 °C for 1000 h). And, the Fe addition had an obvious influence on the volume fraction of γ′ precipitates, γ/γ′ lattice misfit, and the morphology of γ′ precipitates. The higher Fe content enabled the γ matrix to contain more Al and Ti elements, resulting in a lower volume fraction of γ′ precipitates. Simultaneously, the higher content of Al and Ti in γ matrix enlarged the lattice constant of γ matrix and decreased the γ/γ′ lattice misfit from 0.30% to 0.11%, which further induced the morphology of γ′ precipitates changing from the cuboidal shape to the spheroidal shape. Furthermore, the coarsening behavior of γ′ precipitates was analyzed and a corresponding mechanism was proposed that the alloy with Fe addition had a higher coarsening rate of γ′ precipitates during thermal exposure process compared to the alloy without Fe addition, which might result from a lower diffusion activation energy and a larger γ/γ′ interfacial energy.

Effect of Fe addition on the structure and SCR reactivity of one-pot synthesized Cu-SSZ-13

Cu-SSZ-13 has been evidenced to perform well during low temperature range while Fe-SSZ-13 exhibits high NOx conversion at relative high temperatures in standard selective catalytic reduction of NOx with NH3. Considering the respective advantages of Cu and Fe species, we attempt to combine these two elements to overcome single metal deficiency and to construct a more efficient catalyst for NH3-SCR over a broader temperature window. A series of Fe-Cu-SSZ-13 catalysts were prepared by ion exchange method on the basis of one-pot synthesized Cu-SSZ-13. The influence of concentrations of Fe(NO3)3 and exchanging time was considered in the preparing process, and the obtained catalysts were applied to test activity under standard SCR reaction. The superior performance with a moderate Fe/Cu ratio of 1.29 could be attributed to the co-effect of multiple active species, namely Cu(OH)+ and Fe(OH)2+ as well as oligomeric iron. The dominant Cu(OH)+ species in Fe-Cu-SSZ-13–1.29 may account for the excellent low temperature (< 200 oC) performance, while isolated Cu2+ and abundance of Fe ion monomers/oligomer species may be active at higher temperatures. Larger Fe2O3 particles descend the NOx elimination either by blocking the pores in zeolites or increasing the NH3 oxidation ability at high temperature. In-situ DRIFTS studies showed several important intermediates (ad-NO2, NO+, NO3-, NO2-, Cu(Fe)-NH3, NH4NO3), and both nitrite and nitrate route are proposed to be the standard SCR reaction mechanism at low temperatures.

Aluminium-Assisted Alloying of Carbon Steel in Submerged Arc Welding: Application of Al-Cr-Ti-Cu Unconstrained Metal Powders

Al assisted alloying of carbon steel in Submerged Arc Welding (SAW) by Al-Cr-Ti-Cu unconstrained metal powders is applied. A base case without metal powder additions is compared to two metal powder addition schedules, Al-Cu-Ti and Al-Cu-Ti-Cr. Al powder is used as a deoxidiser element to control the oxygen partial pressure at the weld pool–molten flux interface to ensure that most of the Ti and Cr metal powder is transferred into the weld pool and that the weld metal ppm O is controlled within acceptable limits of 200 to 500 ppm O. The likely sequence of alloy melt formation is deduced from the relevant alloy phase diagrams. The effect of Fe addition into the initial Al-Cu-Ti and Al-Cu-Ti-Cr alloy melt is illustrated in thermochemical calculations. Increased metal deposition productivity with metal powder addition in SAW is confirmed. The metal deposition rates increased by 19% and 40% when Al-Cu-Ti and Al-Cu-Ti-Cr powders were applied at the same weld heat input used in the absence of metal powder additions.