Isothermal corrosion Fe_3Si alloy in liquid zinc

The isothermal corrosion testing, microscopic examination and the performance of Fe3Si alloy as materials of construction for bath hardware in continuous hot-dipping lines were studied. The corrosion of Fe3Si alloy in molten zinc was controlled by attacking the grain boundaries preferentially. Aluminum reacted with iron of Fe3Si alloy firstly while the samples were immersed in molten zinc, although aluminum contents in the molten zinc were very low. The phase of reaction product was thought to be Fe2Al5. The corrosion rate of the Fe3Si alloy in molten zinc was determined to be approximately 2.9×10^-3 mm/h, therefore the liquid zinc corrosion resistance of Fe3Si alloy was very weak.

TEMPERATURE DEPENDENCE OF PERMEABILITY OF Co_(66)Fe_4Mo_2Si_(16)B_(12) ALLOY

At different annealing temperatures, the saturation magnetostrictions and the correlation between the permeability μi and the temperature T （μi-T curves） of the Co66Fe4Mo2Si16B12 alloy were investigated using a small-angle magnetization tester and core tester. The experimental results showed that the μi-T curves had different shapes at different ranges of annealing temperature; the permeability μi of the alloy improved with the increase of the annealing temperatures below 460℃; when the alloy was annealed above 480℃, the poor magnetic properties were considered to be caused by larger saturation magnetostriction.

Tribological properties improvement of conventionally-cast Al−8.5Fe−1.3V−1.7Si alloy by multi-pass friction stir processing

The effect of multi-pass friction stir processing(FSP)on the tribological properties of conventionally-cast Al−8.5Fe−1.3V−1.7Si(FVS0812)alloy was investigated.The pin-on-disk dry sliding wear tests were conducted at room temperature under the applied pressures of 0.25,0.50,and 0.75 MPa.The results showed that FSP substantially refined and improved the distribution of coarse¸-Al_(13)Fe4 platelets andα-Al_(12)(Fe,V)_(3)Si intermetallics in the microstructure of alloys and eliminated the intermetallic-related defects.Consequently,the mechanical properties of the alloys,especially their ductility,were improved,which enhanced the stability of the protective tribolayer formed on their worn surfaces.According to the wear test results,the FSPed samples showed improved tribological properties especially at the higher applied pressures.For instance,at the applied pressure of 0.75 MPa,the wear rate and average friction coefficient of four-pass FSPed sample were lower than those of the base as-cast sample by 97%and 52%,respectively.SEM examination of the worn surfaces and wear debris also demonstrated that the wear mechanism changed from severe delamination/abrasion and microcracking of the tribolayer in the as-cast samples to mild delamination/abrasion and minor plastic wear in the FSPed samples.

Influence of Neodymium on Amorphizability of RS Al-Fe-V-Si-Nd Alloys:An Investigation Using Time Dependent Nucleation Theory

Time dependent nucleation theory was applied to calculate the incubation time required for α Al nucleation in rapid solidified (RS) Al Fe V Si Nd alloys. The nucleation rates were calculated as a function of temperature, and the critical cooling rates required for the formation of amorphous α Al at different neodymium concentrations were calculated too. The addition of neodymium increases the amorphizablity of α Al by increasing the incubation time and decreasing the nucleation rate and the critical cooling rate. The calculations are fitted to experimental results when liquidus temperatures are estimated from an approximation, which treats Al Fe V Si Nd as quasi binary Al Fe system.

Microstructural and Microhardness Variation of Amorphous Fe_(78)Si_9B_(13) Alloy during Bend Stress Relaxation

The amorphous Fe78Si9B13 ribbons were bend stress relaxed at various temperature well below the crystallization temperature （Tx） for different time. The effect of pre-annealing on the subsequent bend stress relaxation was examined. The variation of the microstructure and microhardness during bend stress relaxation process was studied using X-ray diffraction （XRD）, atomic force microscopy （AFM） and Vickers microhardness test,respectively. Curvature radius of the amorphous Fe78Si9B13 ribbons decreased with increase bend stress relaxation temperature and time. The microhardness of the stress relaxed specimens increased with time at 300℃ due to the forming of nanocrystals during bend stress relaxation. The pre-annealing reduced the decrease rate of the curvature radius of stress relaxed specimens.

Anomalous microstructure and magnetocaloric properties in off-stoichiometric La–Fe–Si and its hydride

In the present work we reported the phase formation, microstructure, magnetocaloric effect and hydrogenation behavior of La-rich La1.7Fe11.6Si1.4alloy. In this off-stoichiometric La（Fe,Si）13alloy, the Na Zn13-type La（Fe,Si）13matrix phase shows faceted grains, with the Cr5B3-type La5Si3 used as the secondary phase distributed intergranularly. Such a peculiar morphology quickly forms upon one day annealing. In La1.7Fe11.6Si1.4alloy, we have observed a significant field dependence of magnetostructural transition temperature（～ 6.3 K/T）, resulting in a large and table-like entropy change（△S～ 18 J/kg·K in 2 T） over a broad temperature range（～ 10 K）. Upon hydrogenation, the maximum value of △S keeps almost unchanged, while the Curie temperature increases up to 350 K. These results indicate that the investigated offstoichiometric La（Fe,Si）13alloy is a promising magnetic material for magnetic refrigerators.

Investigation on the Tensile Properties and Fracture Characteristics of Amorphous Ribbons Fe81.50B1.40Si7.95Nb7.37Cu1.73P0.05

A number of Fe-Si-B amorphous ribbons are made by using melt spinning method. The microstructure, mechanical and other relevant properties of thin amorphous ribbons of Fe81.50B1.40Si7.95Nb7.37Cu1.73P0.05 alloy at room temperature were studied with several equipment including Differential scanning calorimetry (DSC), X-ray diffraction (XRD),Scanning electron microscope (SEM), and tensile machine. Significantly different microstructures exist between the free and wheel face of the thin amorphous ribbons. The free face is smooth while the wheel face is coarse with a great number of micro voids on the surface. Experimental results show that the tensile strength and elastic modulus of thethin amorphous ribbons at room temperature are 1951 MPa and 70 GPa. In addition, the amorphous ribbons possess reasonable tensile elongation (2.46%). The fracture appearance of amorphous ribbons of Fe81.50B1.40Si7.95Nb7.37Cu1.73P0.05 alloyis a mixed mode of ductile and brittle fracture which includes dimples and partial cleavage fracture similar to the crystalline materials. The dimple feature proves that it still has plastic characteristics on the micro scale.

Effect of Temperature on Scale Morphology of Fe-1.5Si Alloy

Because of the effect of silicon on the formation of oxide scale, red scale is the main surface defect of hot rolled Fe-Si plate, making the scale difficult for descaling compared with carbon steel. Thermogravimetric analyzer （TGA） is used to simulate isothermal oxidation process of Fe-1.5Si alloy for 60 min under air condition, and the temperature range is from 700 to 1 200 ℃. Electron probe microanalysis （EPMA） is used to observe cross-sectional scale morphology and analyze elemental distribution of the scale. Relational graph of temperature, scale thickness and scale structure is obtained. It is found that scale structure （outer Fe oxide layer＋inner FeO/Fe2SiO4 layer＋internal Si oxide precipitates） is almost unchanged with temperature except at 1000 and 1 200 ℃. At 1000 ℃ internal Si ox- ide precipitates cannot be found at the subsurface of the alloy, and at 1200 ℃ FeO/Fe2SiO4 not only forms a layer as usual but also penetrates into the outer Fe oxide layer deeply.

Selective Laser Melting of an Al–Fe–V–Si Alloy:Microstructural Evolution and Thermal Stability

Selective laser melting was used to produce an aluminum alloy Al-8.5Fe-1.3V-1.7Si（wt%）. The effects of heat treatment on microstructure evolution and phase stability during long-term thermal exposure of the deposits were investigated. Results show that the microquasi-crystalline phase, Al12（Fe,V）3Si and AlmF e metastable phases coexisted with α-Al in the as-produced alloy. Annealing at 400 ℃ resulted in decomposition of microquasi-crystalline phase and supersaturated α-Al into Al12（Fe, V）3Si phase in the fusion zone, accompanied by the decrease in alloy hardness. The activation energy of this decomposition process was 115 k J/mol. A more homogenous microstructure was obtained after annealing at 400 °C for 60 min,which was resistant to coarsening exposed at 425 °C up to 500 h. The Al12（Fe,V）3Si and AlmF e phases were coarsened at 475 and 525℃ with increasing the exposure time. Coarsening of Al12（Fe,V）3Si phase was attributed to a combination of volume diffusion and grain boundary diffusion mechanism of Fe. Heat treatment at 600℃ resulted in accelerated microstructure coarsening and formation of large-sized equilibrium phases, which signi？cantly degraded the room temperature microhardness.

Tribological Properties of Nanostructured Al/Al_(12)(Fe,V)_3Si Alloys

Tribological behavior of nanostructured pure Al and Al–Al12（Fe,V）3Si alloys containing 27（FVS0812） and 37（FVS1212） vol% of Al12（Fe,V）3Si precipitates was investigated. All samples were prepared using mechanical alloying followed by hot pressing. Wear tests were performed at room temperature using a pin-on-disk machine. Results showed that the presence of Al12（Fe,V）3Si precipitates increases the wear resistance of nanostructured Al, and the wear resistance increases with increasing the Al12（Fe,V）3Si content. Scanning electron microscopy images of worn surfaces and wear debris demonstrated that abrasion and adhesion are the governing wear mechanisms for the nanostructured FVS0812 alloy at 2 and 5 N normal loads, whereas for the nanostructured FVS1212 alloy, the dominant wear mechanism is abrasion at these loads. A mechanically mixed layer（MML） containing Fe and O was formed on the worn surfaces of FVS0812 and FVS1212 samples at 10 N normal load. Formation and delamination of MML controls the wear behavior of these samples at the normal load of 10 N. It is also found that the presence of Al12（Fe,V）3Si precipitates decreases the friction coefficient of nanostructured Al.

Synchronously Improving the Thermal Conductivity and Mechanical Properties of Al–Si–Fe–Mg–Cu–Zn Alloy Die Castings Through Ultrasonic-Assisted Rheoforming

An ultrasonic vibration-assisted air-cooled stirring rod process(ACSR+UV)was used to efficiently prepare a large-volume semisolid slurry with a mass of more than 40 kg.A low-cost Al–Si–Fe–Mg–Cu–Zn die-casted alloy with high thermal conductivity,high plasticity and medium strength was developed.The alloy was used to manufacture large,thin-walled parts for 5 G base stations by using the ACSR+UV rheological die-casting(ACSR+UV R-DC)process.Investigations were performed on the microstructure,porosity,mechanical properties,fracture behaviour and thermal conductivity of the ACSR+UV R-DC alloy,which was then compared to traditionally die-casted(T-DC)and ACSR R-DC alloys.The mechanisms for the microstructural refinement and enhancement of the mechanical and thermal conductivity performances of the ACSR+UV R-DC alloy were also analysed.The results showed that the ACSR+UV process increased the nucleation rate of the melt due to the increase in the nucleation area and the generation of cavitation bubbles.A radial-and an axial-forced convection was also generated inside the melt under the combined effects of acoustic flow and mechanical stirring,thereby homogenising the melt composition field and the temperature field.Therefore,the ACSR+UV R-DC process not only refined the primaryα-Al(α_(1)-Al),the eutectic silicon and the secondaryα-Al(α_(2)-Al),but also greatly improved the morphology and the distribution of the β-Al5FeSi phase.The mechanical properties of the ACSR+UV R-DC alloy were higher than those of the T-DC and the ACSR R-DC alloys.Compared to the T-DC alloy,the ultimate tensile strength,elongation and yield strength of the ACSR+UV R-DC alloy were increased by 34%,122%and 19%,respectively.This was because the ACSR+UV R-DC technique gave the alloy the characteristics of high density,fine sphericalα1-Al grain and a fine and uniform β-phase,which improved the fracture behaviour of the alloy.The thermal conductivity of the ACSR+UV R-DC alloy was 184 W/(m K),which was 10.2%and 3.4%higher than that of T-DC and ACSR R-DC alloys,respectively.This was because the refined eutectic silicon and β phases in the ACSR+UV R-DC alloy facilitated an easier electron flow through the eutectic region,and the decrease in porosity increased the effective area of heat conduction.

Microstructure,magnetic and magnetocaloric properties of Fe_(2-x)Mn_xP_(0.4)Si_(0.6) alloys

The present work is devoted to investigating the microstructure,magnetism and magnetocaloric effects of Si- and Mn-rich FeMn(P,Si) alloys.The Mn-substituted alloys with Fe_(2-x)Mn_xP_(0.4)Si_(0.6)(x=1.25,1.30,1.35,1.40,1.45 and 1.50) were prepared by high-energy ball milling and solid-state reaction.Experimental results show that the alloys crystallized into a majority Fe_2P-type hexagonal structure,coexisting with minor amounts of(Mn,Fe)_3Si and(Mn,Fe)_5Si_3 phases.The Curie temperature decreased linearly from 321 to 266 K with increasing Mn content from 1.25 to 1.50 in Fe_(2-x)Mn_xP_(0.4)Si_(0.6) alloys.The first-order magnetic phase transition became weakened and the second-order magnetic phase transition became dominated with increasing Mn content.Fe_(0.75)Mn_(1.25)P_(0.4)Si_(0.6) alloy presents a maximum isothermal magnetic-entropy changes of 7.2 J(kg K)^(-1) in a magnetic field change of 0-1.5 T.The direct measurement shows that Fe_(0.7)Mn_(1.3)P_(0.4)Si_(0.6) and Fe_(0.65)Mn_(1.35)P_(0.4)Si_(0.6) alloys exhibit a maximum adiabatic temperature change of 1.8 K in a magnetic field change of 0-1.48 T.The thermal hysteresis for all alloys is less than 4 K.These experimental results reveal that Fe_(2-x)Mn_xP_(0.4)Si_(0.6) alloys could be a candidate material for magnetic refrigeration.

Laser Powder Bed Fusion Processing of Soft Magnetic Fe–Ni–Si Alloys: Effect of Hot Isostatic Pressing Treatment

Laser powder bed fusion(L-PBF)-processed high-silicon steel has great advantages in freely designed electric engines,and various studies have been conducted in this field.However,the analysis of both the mechanical and magnetic properties,focusing on the multiscale microstructure under as-fabricated and heat-treated conditions,which is indispensable for industrial applications,has not been performed.In this study,an Fe–Ni–Si sample was fabricated using the L-PBF process.Subsequently,the following hot isotropic pressing(HIPing)process was employed as a post heat treatment step for the Fe–Ni–Si alloys.The effects of HIPing on the microstructure were investigated,focusing on the metastable stable phase transformation in the Fe–Ni–Si system.X-ray diffraction results showed single-phase fccγ(Fe,Ni)in the L-PBF-processed samples before and after HIPing.Moreover,the acicular Ni/Si-rich structure(formed in the as-fabricated L-PBF sample because of its high cooling rates)transformed to the equilibrium austenite,Ni3Si,and FeNi3 phases during HIPing.After HIP,the compressive modulus and strength increased from 11 GPa and 650 MPa to approximately 18 GPa and 900 MPa,respectively.The magnetic properties were evaluated via a hysteresis loop,and the coercivity increased from 1.8 kA/m and to 2.9 kA/m after the HIPing process.

Effects of Mechanical Milling and Sintering Temperature on the Densification, Microstructure and Tensile Properties of the Fe–Mn–Si Powder Compacts

This work reported on the effects of mechanical milling and sintering temperature on the densification,microstructure and mechanical properties of the Fe–28Mn–3Si（wt%） alloy. Elemental Fe, Mn and Si powders were used as the starting materials, and two batches of powder mixture were prepared： one was blended elemental（BE） powder mixture; the other was mechanically milled（MM） powder mixture milled for5 h using planetary ball milling. Both powder mixtures were pressed under a uniaxial pressure of 400 MPa,and subsequently sintered in a high vacuum furnace for 3 h at 1000, 1100, 1200 and 1300 °C. It was found that Mn depletion region（MDR） was formed on the surface of all the sintered samples. The sintered BE compacts had a low density（〈68.2%） at all temperatures, while the density of the sintered MM compacts increased drastically from ~65% at 1000 °C to ~91% at 1300 °C. All the sintered MM compacts were composed of a predominant γ-austenite and minor ε-martensite. In comparison, additional（Fe, Mn）3Si phase was observed in the BE alloys sintered at 1000 °C, and a single α-Fe phase was identified in the BE compact sintered at 1300 °C. The tensile properties of the sintered MM compacts increased significantly with the temperature and were significantly higher than those of their BE counterparts.