Effect Of Fe Addition Research Articles

Influence of Fe addition on annealing behaviors of a phosphorus containing brass

Abstract Effect of Fe addition on annealing behaviors of cold rolled Cu-30Zn-0.1P brass was investigated in terms of hardness behavior, microstructure development and microtexture evolution. A maximum increase of about 20% in hardness was observed with the addition of Fe before and after annealing. Fe2P particles were found dispersed in Cu-30Zn-0.1P-0.5Fe alloy before and after annealing and they showed great pinning effects and resulted in inhibited recrystallization, grains refinement and thermal stability enhancement. It is also indicated by kernel average misorientation (KAM) maps that a higher dislocation density and energy were stored in the sample with the addition of Fe. As a result, the second phase strengthening and grain boundary strengthening were found to be responsible for the hardness increment for the alloy with the Fe addition. Besides, a higher fraction of Brass texture was found at the beginning of annealing in Cu-30Zn-0.1P-0.5Fe alloy. The results also showed that Brass texture then translate into Brass-R and (55;30;0) textures during annealing, resulting in high fractions of Brass-R and (55;30;0) textures in Cu-30Zn-0.1P alloy with the addition of Fe after annealing.

Effect of Fe addition on microstructure and electrical properties of Co1.5Mn1.5−xFexO4 (0.2 ≤ x ≤ 1.0) NTC thermistors

In this work, the effect of Fe addition on microstructure and electrical properties of Co1.5Mn1.5−xFexO4 (0.2 ≤ x ≤ 1.0) NTC thermistors was studied. The added Fe did not affect the crystalline structure and formed a single cubic spinel phases. The density of Co1.5Mn1.5−xFexO4 samples decreased significantly with increasing Fe content. The values of ρ25, ρ50, B25/50, and Ea of ceramic samples were in the range of 2283–14273 Ω cm, 730–5157 Ω cm, 3701–3991 K, and 0.3196–0.3445 eV, respectively. This means that the electrical properties can be adjusted to desired values, depending on Fe content. The values of relative resistance drift ΔR/R0 (0.2 ≤ x ≤ 1.0) had a minimum value when x = 0.4, after aging test for 500 h.

Consideration of enthalpic and entropic energy contributions to the relative rates of chalcopyrite dissolution in the presence of aqueous cationic impurities

To understand the effect of aqueous impurities on chalcopyrite dissolution during acid metalliferous drainage and hydrometallurgical processes, batch dissolution experiments were carried out at 650 and 750mV (SHE), pH1 and 35–75°C in the presence or absence of aqueous cationic additives. Activation energies (Ea) for chalcopyrite dissolution in the presence of additives at 750mV, derived using a modified ‘time to a given fraction’ method, demonstrate that Ea varies with reaction extent. The overall trend of evolution from interface- to transport-controlled mechanism was independent of additive type or addition. This suggests that it is not primarily variation in the enthalpy of dissolution that controls the significant changes in relative dissolution rates on addition of additives.Rather, the relative dissolution rates on addition of aqueous cations are found to relate to the M–O framework volume (M and O being the cationic additive and oxygen within H2O in the first sphere of hydration, respectively). There is good inverse linear correlation between this volume and the relative dissolution rate per unit ionic strength which varies as K+>Al3+>no additive>Mg2+>Na+>Ca2+. It is proposed that this effect is related to the relative strength of hydration of the additives with the commensurate entropic effect on solute hydration being advantageous for chalcopyrite dissolution on K+ and Al3+ addition and detrimental for the other additives. H4SiO4, the dominant aqueous species upon Si addition under the conditions examined, has low affinity for water, resulting in a detrimental entropic contribution to solute hydration and dissolution. The effect of Fe addition on relative dissolution rate is convoluted by the role of Fe3+ as the primary oxidant for chalcopyrite dissolution. On addition of aqueous Fe to dissolution at 750mV, the effect is detrimental due to the detrimental effect on the entropy of hydration of the solute and the relative abundance of Fe3+. At 650mV the effect of the greater presence of Fe3+ due to Fe addition dominates and the dissolution rate is enhanced.

Martensitic transformation and shape memory behavior of Ti-V-Al-Fe lightweight shape memory alloys

Effects of Fe addition on martensitic transformation and shape memory behavior of Ti-V-Al-Fe alloys were investigated. A little amount of Fe addition reduces martensitic transformation temperature rapidly and enhances shape memory effect of Ti-V-Al alloy. Alloy with an optimal Fe content, which is Ti-13V-3Al-1Fe, shows the largest recoverable strain of 5.8% and highest recovery stress of 250 MPa when pre-strain is 6%. Meanwhile, Ti-13V-3Al-1Fe alloy has a large elongation of 30%.

Effects of Fe addition on the mechanical and thermo-mechanical properties of SiC/FeSi2/Si composites produced via reactive infiltration

Remaining silicon in SiC-based materials produced via reactive infiltration limits their use in high-temperature applications due to the poor mechanical properties of silicon: low fracture toughness, extreme fragility and creep phenomena above 1000°C. In this paper SiC–FeSi2 composites are fabricated by reactive infiltration of Si–Fe alloys into porous Cf/C preforms. The resulting materials are SiC/FeSi2 composites, in which remaining silicon is reduced by formation of FeSi2. For the richest Fe alloys (35wt% Fe) a nominal residual silicon content below 1% has been observed. However this, the relatively poor mechanical properties (bending strength) measured for those resulting materials can be explained by the thermal mismatch of FeSi2 and SiC, which weakens the interface and does even generate new porosity, associated with a debonding phenomenon between the two phases.

The Effect of Fe Addition on the Mechanical Properties of Ti–6Al–4V Alloys Produced by the Prealloyed Powder Method

The Effect of Fe Addition on the Mechanical Properties of Ti–6Al–4V Alloys Produced by the Prealloyed Powder Method

Effects of Fe addition on the structure and catalytic performance of mesoporous Mn/Al–SBA-15 catalysts for the reduction of NO with ammonia

Mesoporous Al–SBA-15 has been synthesized by a hydrothermal method and used as a support for Mn/Al–SBA-15, Fe/Al–SBA-15, and Mn–Fe/Al–SBA-15 catalysts. XRD, N2 sorption, XPS, H2-TPR and activity tests have been used to assess the properties of catalysts. The Mn–Fe/Al–SBA-15 catalyst exhibited a higher SCR activity than Mn/Al–SBA-15 or Fe/Al–SBA-15 due to a synergistic effect between Mn and Fe. After the addition of Fe, the binding energy of Mn 2p3/2 on Mn–Fe/Al–SBA-15(573) decreased by about 0.4eV and the Mn4+/Mn3+ ratio decreased to 1.10. The appropriate Mn4+/Mn3+ ratio may have a great effect on the reduction of NO over Mn–Fe/Al–SBA-15(573) catalyst.

Effect of Fe additions on microstructure and mechanical properties of a multi-component Nb–16Si–22Ti–2Hf–2Al–2Cr alloy at room and high temperatures

The phase constitutions, microstructural evolutions, and mechanical properties of Nb–16Si–22Ti–2Hf–2Al–2Cr–xFe alloys (where x = 1, 2, 4, 6 at.%, hereafter referred to as 1Fe, 2Fe, 4Fe and 6Fe alloys, respectively) prepared by arc-melting were investigated. It was observed that the nominal Fe content affected the solidification path of the multi-component alloy. The as-cast 1Fe alloy primarily consisted of a dendritic-like NbSS phase and (α+γ)-Nb5Si3 silicide, and the as-cast 2Fe and 4Fe alloys primarily consisted of an NbSS phase, (α+γ)-Nb5Si3 silicide and (Fe + Ti)-rich region. In addition to the NbSS phase, a multi-component Nb4FeSi silicide was present in the as-cast 6Fe alloy. When heat-treated at 1350 °C for 100 h, the 1Fe and 6Fe alloys almost exhibited the same microstructures as the corresponding as-cast samples; for the 2Fe and 4Fe alloys, the (Fe + Ti)-rich region decomposed, and Nb4FeSi silicide formed. The fracture toughness of the as-cast and heat-treated Nb–16Si–22Ti–2Hf–2Al–2Cr–xFe samples monolithically decreased with the nominal Fe contents. It is interesting that at room temperature, the strength of the heat-treated samples was improved by the Fe additions, whereas at 1250 °C and above, the strength decreased, suggesting the weakening role of the Nb4FeSi silicide on the high-temperature strength. As the nominal Fe content increased from 1 at.% to 6 at.%, for example, the 0.2% yield strength increased from 1675 MPa to 1820 MPa at room temperature; also, the strength decreased from 183 MPa to 78 MPa at 1350 °C.

Flow boiling heat transfer enhancement on copper surface using Fe doped Al2O3–TiO2 composite coatings

In the present work, flow boiling experiments were conducted to study the effect of spray pyrolyzed Fe doped Al2O3–TiO2 composite coatings over the copper heater blocks on critical heat flux (CHF) and boiling heat transfer coefficient. Heat transfer studies were conducted in a mini-channel of overall dimension 30mm×20mm×0.4mm using de-mineralized water as the working fluid. Each coated sample was tested for two mass fluxes to explore the heat transfer performance. The effect of Fe addition on wettability and porosity of the coated surfaces were measured using the static contact angle metre and the atomic force microscope (AFM), and their effect on flow boiling heat transfer were investigated. A significant enhancement in CHF and boiling heat transfer coefficient were observed on all coated samples compared to sand blasted copper surface. A maximum enhancement of 52.39% and 44.11% in the CHF and heat transfer coefficient were observed for 7.2% Fe doped TiO2–Al2O3 for a mass flux of 88kg/m2s.

Magnesia-supported potassium oxide catalysts for soot combustion: effect of Fe addition on the catalyst activity and stability

This work shows that loading Fe into the K/MgO catalyst for soot combustion can reduce K volatilization due to the formation of potassium-iron oxide compounds. K/MgO and K–Fe/MgO catalysts were prepared by the impregnation of potassium and iron precursors on MgO, and their activity for soot combustion was assessed by thermogravimetric analysis. Catalysts were characterized by atomic absorption spectroscopy, BET surface area, X-ray diffraction and X-ray photoelectron spectroscopy. Fe addition on K/MgO catalyst enhanced its catalytic activity, which is ascribed to a larger K retention into the catalysts either as potassium oxides or as K–Fe–O compounds. The non-stoichiometric potassium oxide (KXOY) is considered as the active phase of this kind of catalysts; it tends to migrate to the surface and to coat the Fe and K–Fe oxides compounds, increasing the surface concentration of active sites for soot combustion. Thus, molecular oxygen from the gas phase is activated over these potassium oxides to generate highly active oxygen species that finally oxidize the carbonaceous matter through an oxygen-transfer mechanism.

Effect of Fe Addition on the Microstructure Formation and Mechanical Properties of Ti-2.0, 3.0at%Mo Alloys

Abstract. Ti-Mo based alloys have been used as biocompatible materials. Recently the positive use of inexpensive alloying elements becomes important to develop low cost Ti alloys. The purpose of the present study was to reveal the effect of Fe in Ti-Mo alloy addition on the microstructure formation and mechanical properties. Ti-(2.0, 3.0)at%Mo-(0.0~2.0)at%Fe alloys were arc-melted. The alloy buttons were hot-rolled into about 2.0 mm thick sheets at 10731223 K. Specimens -solid-solution-treated at 1273 K in β phase field were quenched into iced brine. X -ray diffractometry was used to identify phases in the specimens. Microstructures were examined by both optical and transmission electron microscopies. Hardness Young's modulusand of the alloys were evaluated. Addition of Fe in Ti -Mo alloys promote d the formation of athermal omega and increase d in hardness. As-quenched Ti-3at%Mo alloy exhibited mixture of α' and α martensites. The Young's modulus of it was 76 GPa. Ti-2at%Mo-1at%Fe alloy, replacement of 1at%Mo (expensive) by 1at%Fe (inexpensive) from Ti-3at%Mo, also exhibited mixture of α' and α martensites with the Young's modulus of 85 GPa. Hardness of Ti -2at%Mo-1at%Fe alloy, 329Hv, is greater than that of Ti -3at%Mo alloy, 257 Hv. -2at%MoTi-1at%Fe is thought to be a candidate material for a low cost bone replacement Ti alloy with low Young's modulus.

Martensitic Transformation and Related Properties of AuTi-FeTi Pseudobinary Alloys

The effects of Fe addition on martensitic transformation and mechanical properties of AuTi were investigated in this study. It was found that B2 parent phase is stabilized by the Fe addition and that AuTi can contain at least 20mol%Fe. The lattice deformation strain evaluated from θ-2θ X-ray diffraction analysis (XRD) is not significantly changed by the Fe addition. The decrease in Ms evaluated by differential scanning calorimetry (DSC) is-40K/mol%Fe. Tensile tests revealed that, with increasing Fe content, the yield stress decreases up to about 13mol%Fe, largely increases up to 15mol%Fe and then decreases gradually. By taking into account XRD and DSC results, these behaviors are judged to correspond to reorientation of martensite variants, stress induced martensitic transformation and slip deformation of parent phase, respectively. The values of dσSIMT/dCFe and dσSIMT/dT are evaluated to be-170MPa/mol%Fe and-4.3MPa/K, respectively. The elongation is degraded with increasing Fe content from 8% in AuTi (0mol%Fe, martensite phase) to 2% in AuTi-20mol%Fe (parent phase) depending on the apparent phase.

Insight into the Effects of Fe Addition on the Local Structure and Electronic Properties of SrTiO3

This paper reports an experimental and theoretical investigation of the effects of adding Fe to the perovskite strontium titanate SrTiO3. The effects include changes in the short-order range structure as well as in the electronic and electrical properties. X-ray diffraction analysis reveals that the SrTi1–xFexO3 network shrinks with increasing Fe content, while X-ray absorption spectroscopy measurements of the Ti and Fe K-edge revealed the presence of some under-coordinated TiO5 units created because of the partial replacement of Fe3+ ions in the Ti4+ site. UV–visible absorption spectra indicated a reduction in optical gap with increasing Fe content. The electronic structure and spin densities of STFO with x = 0, 0.0625, 0.125, 0.5, and 1 are calculated by the DFT method at the B3LYP computational level, showing a Jahn–Teller distortion of O atoms surrounding the Fe as well as the formation of under-coordinated TiO5 units. From the electrical viewpoint, the results show that STFO is a mixed (ionic and electronic) conductor and that the electronic contribution becomes dominant with increasing Fe content.

Electrical Resistivity of Fe-Bearing Sn1Ag0.5Cu Lead-Free Solder Alloys

This paper reports on the effect of Fe addition in the range of 0.1 wt.% to 0.5 wt.% on the electrical resistivity of the Sn-1Ag-0.5Cu (SAC105) solder alloy. The electrical resistivity is characterized by the four-point probe technique. Results showed that the Fe-bearing SAC105 solder alloys exhibit lower electrical resistivity compared with the standard SAC105 solder alloy. Moreover, the electrical resistivity further decreases with increasing the amount of Fe addition. As Fe is a low-cost and non-hazardous element, along with the high mechanical reliability, the Fe-bearing SAC105 solder alloys also demonstrate good electrical characteristics, and hence may be an attractive candidate for a low cost, reliable formulation for lead free solders in electronics packaging.

Ti-Zr-Be-Fe quaternary bulk metallic glasses designed by Fe alloying

A series of Ti-Zr-Be-Fe bulk metallic glasses (BMGs) with good glass-forming ability (GFA) and high specific strength have been developed. With different alloying routes and content of Fe, it is found that these alloys exhibit different GFA and mechanical properties. The effects of Fe addition on the GFA and mechanical properties of Ti-Zr-Be alloy are systemically investigated. The possible mechanisms for the improvement or damage to the GFA by addition of Fe can be interpreted in view of the mixing enthalpy, atomic size differences and electronegativity differences of the alloys, while the mechanical properties strongly depend on the Poisson’s ratio and free volume concentration. The experimental results also show that alloying technology is an effective method to improve the GFA and mechanical properties of Ti-Zr-Be glassy alloy.

Influence of Fe content on corrosion and hydrogen pick up behavior of Zr–2.5Nb pressure tube material

The effects of Fe addition in the range of 300–1250ppm in cold worked stress-relieved Zr–2.5Nb pressure tube on oxidation and hydrogen pick up behavior have been studied after 415°C steam autoclaving. Microstructure and micro-chemistry of second phase and precipitates were characterized using electron microscope. Addition of 800ppm Fe in Zr–2.5Nb alloy led to better oxidation resistance. With further addition of Fe no significant improvement of oxidation resistance was observed but hydrogen-pickup was found to increase. Zr–Nb–Fe bearing precipitates were observed in Zr–2.5Nb alloy containing 800ppm Fe. Further addition of Fe led to formation of Zr–Fe intermetallic. The chemical state of oxide has been determined by X-ray photo electron spectroscopy. Grazing Incidence X-ray Diffraction revealed that oxide in alloys with higher Fe, contained a higher fraction of tetragonal-Zirconia which is indicative of a protective oxide film and hence better oxidation resistance of the alloy.

Promotional effect of Fe on perovskite LaNixFe1−xO3 catalyst for hydrogen production via steam reforming of toluene

The effect of Fe addition on catalytic activity and stability of LaNixFe1−xO3 perovskite catalyst was investigated for hydrogen production via steam reforming of tar using toluene as a model compound. The addition of Fe to LaNiO3 catalyst at the optimum amount enhanced the catalytic performance in steam reforming of toluene. LaNi0.8Fe0.2O3 catalyst shows the best performance in terms of catalytic activity and stability for 8 h of reaction time. The catalyst characterization indicates the presence of Ni-rich Ni–Fe smaller bimetallic particles, strong metal support interaction, and lower carbon deposition rate on LaNi0.8Fe0.2O3 catalyst. The synergy between Ni and Fe atoms on the small Ni–Fe bimetallic particles is crucial for high activity of the LaNi0.8Fe0.2O3 catalyst. In addition, the strong interaction between metal and support on the LaNi0.8Fe0.2O3 catalyst can prevent metal sintering, thus, achieving high catalytic stability.

Investigation of the structure and mechanical properties of as-cast Ti-Cu-based alloys

As-cast Ti-Cu-based alloys containing 1000 mass ppm of boron were investigated in the present work. With respect to a base compositional formula of (Ti-Zr)49.5+x(Cu-Ni)49.5−xFe1, we investigated the effect of sample size on the phase constitutions and related mechanical properties of the alloys, with the goal of producing crystal-glassy composites. The effect of Fe addition on the phase constitution of as-cast Ti-Cu-based alloys was also investigated, and the obtained results were compared with those of our previous studies, in which we investigated similar alloys containing no Fe.It was demonstrated that the addition of Fe leads to the formation of a CuTi2 intermetallic compound, while decreasing the cooling rate (by increasing the diameter of the as-cast billets) makes the formation of the CuTi2 intermetallic compound more favourable. The best combination of mechanical properties was obtained for the alloys containing no CuTi2 intermetallic compound.

Poisoning-free effect of calcium on grain refinement of Mg–3%Al alloy containing trace Fe by carbon inoculation

Mg-3%Al alloy was modified by combining Ca addition with carbon inoculation. The effects of Fe addition and addition sequence on the grain refinement were investigated. A higher grain refining efficiency could be obtained for the Mg–Al alloy modified by combining Ca addition with carbon inoculation. Fe addition and addition sequence had no obvious effect on the grain refinement. Ca addition could effectively avoid grain-coarsening resulting from Fe in the carbon-inoculated Mg–Al alloy. The Al-C-O particles, actually being Al4C3, should act as potent substrates for α-Mg grains in the sample treated by combining Ca addition with carbon inoculation. However, the duplex-phase particles of Al4C3 coated on Al-Fe or Al-C-Fe should be the potent substrates for α-Mg grains if Fe existed in the Mg–Al melt. Ca addition can contribute to the formation of the particles of Al4C3 coated on Al-Fe or Al-C-Fe, regardless of the Fe addition sequence. The poisoning effect of Fe was effectively inhibited in the carbon-inoculated of Mg-Al alloy due to Ca addition, namely, Ca has a poisoning-free effect.

Effect of Fe on the Precipitate Characteristics and Out-of-Pile Corrosion Behavior of Zr-1Nb-xFe Alloys

The effects of Fe addition on the precipitate characteristics and out-of-pile corrosion behavior of Zr-1Nb-xFe alloys, with x=0, 0.2 and 0.4 respectively, were investigated. The experimental results showed that the alloy with the composition of Zr-1Nb-0.4Fe had the best corrosion resistance and the alloy with the composition of Zr-1Nb-0.2Fe had the worst corrosion resistance. The relationship between the corrosion behavior and the microstructures including precipitate characteristics was discussed, and the elements contents, area fraction, as well as the mean diameter of the precipitate were analyzed. The β-Nb precipitate was found in Zr-1Nb alloy, both Zr (Nb,Fe)2 precipitate and β-Nb precipitate were formed in Zr-1Nb-0.2Fe alloy, while only Zr (Nb,Fe)2 precipitate was observed in Zr-1Nb-0.4Fe alloy. It has been found that the size of precipitates increased with the increasing of Fe content. This work indicated that the Fe content dominates the crystal structure, volume fraction and the element contents of the precipitate, which affect the corrosion resistance of Zr alloy.