Effect Of Boron Addition Research Articles

Boron addition in a non-equiatomic Fe50Mn30Co10Cr10 alloy manufactured by laser cladding: Microstructure and wear abrasive resistance

A non-equiatomic Fe50Mn30Co10Cr10 alloy was prepared by laser cladding, and the effects of boron addition on the microstructure, hardness and abrasive wear-resistance were investigated. Elemental powders were mixed using an attritor mill for 30 h and then applied by laser cladding on a stainless steel 316L substrate. The effect of boron addition (0.1, 0.66 and 5.40 at%) on the alloy microstructure was assessed using optical and electron microscopy, and the phase composition was studied using X-ray diffraction. The laser claddings were exposed to abrasive wear conditions using the dry sand/rubber wheel test. The microstructure of the laser claddings exhibited columnar dendrites formed by two crystalline structures (fcc and hcp) with the same chemical composition. The hcp structure was the result of the partial martensitic transformation of the fcc structure. Boron addition led to the formation of a eutectic phase along the interdendritic regions with a crystalline structure consistent with M2B-type borides (M = Cr, Fe). Hardness and abrasive wear-resistance of the laser claddings were strongly influenced by boron content. When boron content was increased from 0 at% to 5.40 at% the microhardness of the material was from 291 HV to 445 HV. Similarly, the boron content improved the behaviour against abrasive wear due to the increased volume fraction of borides in the microstructure. The high content of the boride phase in the laser cladding with 5.40 at% B allowed reducing the abrasive wear rate by more than 30% when compared with the alloy without boron content.

Investigation of boron usability in rock wool production

The effect of boron addition on basalt and basalt-dolomite mixtures was tested for rock wool production. The melting temperatures and the viscosities of the melts were determined and SEM and EDS analysis on some samples were done to find out the effect of boron addition. It was observed that boron addition lowered the melting temperatures noticeably, slight increases in the viscosities were at acceptable levels and no negative structural changes were caused. It was concluded that boron could be added for the rock wool production and the quantity to be used could be adjusted considering the melting temperature and the viscosity value.

The corrosion behavior of the Ni3Al intermetallic materials obtained by SPS in alkali solutions

The effect of boron additives on the corrosion resistance of Ni3Al intermetallic obtained by spark plasma sintering of powder mixtures with preliminary mechanical activation in alkali water is studied. It is established that monophasic nickel aluminide and alloyed with 0.1% B has high corrosion resistance in boiling solutions of strong alkalis, such as potassium and sodium hydrate. The corrosion rate in such medium is less than 0.05 mm/year, even when corrosion activators are added into the solution. High corrosion resistance is due to the processes of passivation of the material during the interaction of the surface of the material with the solution. Solutions of weak alkalis have a more aggressive effect on sintered nickel aluminide. It is shown that the corrosion rate of intermetallic in aqueous ammonia is 0.22…0.24 mm/year. With the boron addition, the corrosion rate increased to 0.29 mm/year.

Effect of boron addition on the rolling contact fatigue strength of Fe-Ni-Mo-B-C sintered alloys

Effect of boron addition on the rolling contact fatigue strength of Fe-Ni-Mo-B-C sintered alloys

Photocatalytic Hydrogen Production by Boron Modified TiO2/Carbon Nitride Heterojunctions

AbstractBoron‐doped anatase TiO2 particles were effectively coupled with carbon nitride (CN) forming nanocomposites. The materials were fully characterized by DR‐UV‐Vis, N2 adsorption‐desorption isotherms, XRD, Raman, FTIR, TGA, XPS, TEM, electron energy loss spectroscopy, photoluminescence, and electron paramagnetic spectroscopy (EPR) spectroscopy. The developed heterojunctions were applied as photocatalysts for hydrogen (H2) evolution by the photoreforming process of ethanol under solar irradiation, using minimal amount of Pt nanoparticles (0.1 wt. %) as co‐catalyst. The effects of boron addition and CN content were evaluated and optimized nanocomposite presented 85 % increase in H2 evolution compared with the pure anatase TiO2 catalyst. The observed higher H2 evolution rates were ascribed to improvements in charge formation and separation efficiency due to the B‐dopant and the presence of CN.

Effects of boron addition on microstructures and mechanical properties of Ti-6Al-4V manufactured by direct laser deposition

Large columnar grains with strong texture in direct laser deposited (DLDed) Ti-6Al-4V (Ti-64) is widely reported to cause issues like strong mechanical property anisotropy and poor tensile strength, which make this material unsuitable for many uses in the aerospace industry. In this study, a microstructure refinement investigation was carried out by adding various amounts of boron from 0.05 wt% to 1.0 wt%. The effects of boron additions, even with 0.05 wt%, are very strong on the microstructure refinement. The presence of large columnar grains was eliminated along with the α lath refinement, the grain boundary α elimination and the texture weakening. β reconstruction results showed that boron is very effective in the β grain refinement and the β texture weakening, which contributes to the transformed α lath refinement and the α texture weakening, respectively. Furthermore, the tensile strength of DLDed Ti-64 with different boron additions is improved. A good balance of the tensile strength and ductility, with considerably reduced anisotropy, was achieved by adding 0.05 wt% boron. A comprehensive understanding between the boron additions, microstructure refinement and tensile performance improvement was fully established, which could enable greater usage of DLDed Ti-64 in the aerospace industry.

Effects of Boron Addition on the Microstructure and Mechanical Properties of (Ti,Ta)(C,N)-Co Based Cermets

In this work, a titanium–tantalum carbonitride based cermet, with cobalt as the binder phase and boron as a sintering additive, was developed by a mechanically induced self-sustaining reaction process using two different methodologies. The boron additive was added to prevent the formation of brittle intermetallic compounds generally formed during the liquid phase sintering step due to the excessive ceramic dissolution into the molten binder phase. A systematic study was carried out to understand the effects of boron addition on the nature of the phases, microstructure, and mechanical properties of cermets. With the boron addition, the formation of two different boride solid solutions, i.e., (Ti,Ta)B2 and (Ti,Ta)3B4, was observed. Moreover, the nature of the binder was also modified, from the (Ti,Ta)Co2 brittle intermetallic compound (for cermets without boron addition) to ductile and tough (Ti,Ta)Co3 and α-Co phases (for cermets with boron addition). These modifications caused, as a general trend, the increase of hardness and toughness in cermets.

Effect of Boron Addition on Creep Strain during Impression Creep of P91 Steel

In an attempt to understand the effect of boron addition on creep deformation behavior under high stress and high temperature in martensitic P91 steel, impression creep tests were carried out on boron-free P91 (P91) and boron-added P91 (P91B) steels. The experimental program consisted of three steps, i.e., characterization of as-received steels by microhardness, optical microscopy (OM), transmission electron microscopy (TEM), electron backscattered diffraction (EBSD) and wavelength-dispersive spectroscopy (WDS); impression creep tests at 445 MPa and 625 °C on as-received steels; characterization at deformed plastic zones of impression-crept specimens by microhardness, OM, EBSD, TEM and WDS. Impression creep tests were run till a depth of penetration of 1.8 mm was achieved for both cases which ensured a sufficient plastic zone underneath indenter for subsequent microstructural investigations. Coarsening of M23C6 carbides was observed in P91 steel during high-temperature creep loading, which leads to extensive strain hardening in deformed plastic region, resulting in impaired creep performance. On the contrary, dynamic recrystallization in P91B steel results in formation of small strain-free grains during creep loading which are responsible for increased resistance of the material to shear stresses during an impression creep test.

Tunable coefficient of thermal expansion of Cu-B/diamond composites prepared by gas pressure infiltration

Cu-B matrix composites reinforced with diamond particles (Cu-B/diamond) were prepared by gas pressure infiltration (GPI). The effect of boron addition in the range of 0–1.0 wt% on the thermal expansion behavior of the Cu-B/diamond composites was evaluated. The coefficient of thermal expansion (CTE) of the Cu-B/diamond composites initially decreases and then increases with increasing boron content. The minimum CTE value of 4.88 × 10−6/K is obtained at 0.5 wt% B addition, which satisfies the requirement of CTE of semiconductors (range of 4–8 × 10−6/K) for electronic packaging applications. The variation of CTE of the Cu-B/diamond composites is attributed to the formation of interfacial carbides and their morphological evolution. The interface structure evolves from discrete triangular carbides into continuous carbide layer with increasing boron content. The increase in the quantity of discrete carbides enhances the interface, but the formation of continuous carbides impairs the interfacial bonding of the Cu-B/diamond composites. The results suggest that alloying B to Cu matrix is an effective route to tune the coefficient of thermal expansion of Cu/diamond composites.

Effect of Boron Addition and Sintering Atmosphere on Precipitation in Sintered Fe-Mo-C Steels

Sintered steels, with and without boron addition, were prepared from powder compacts of pre-alloyed Fe-1.5Mo powder mixed with varied amounts of graphite (0, 0.1, 0.2, 0.3, and 0.4 wt.%) and hexagonal boron nitride (0 and 0.5 wt.%). Sintering was performed either in hydrogen or in vacuum atmosphere at 1280 °C for 45 minutes. The post-sintering cooling was performed in a furnace that was equivalent to 0.1 °C/s. The sintered boron-free steels showed dual-phase microstructure consisting polygonal ferrite and precipitate-containing grains. Each precipitate-containing grain contained packets, each of which was characterized by lamellar structure with alternating fibrous particles and ferritic laths, when carbon contents were in the range 0.1-0.3 wt.%. All the grains containing fine needle particles decorating ferritic lath boundaries were observed in the sintered Fe-Mo-0.4C steels. Boron addition caused some effects on sintered steels. The action of boron was the formation of grain boundary boride in the vacuum-sintered steels although it was hardly observed in case of hydrogen-sintered steels. Boron also promoted precipitation inside polygonal ferrite grains and along ferritic lath boundaries. The precipitate particle shape was fine needle-like in the sintered boron-containing steels. Due to liquid phase sintering, as a result of eutectic melting, the associated grain growth was observed. Disappearance of grain boundary boride was evidenced in the hydrogen-sintered steels. Without boron addition, hardening of the sintered steels strongly depended on carbon content. With boron addition, all the sintered steels showed high tensile strength and hardness even in the case of no graphite addition. Hardening action by carbon in the sintered boron-containing steels was weaker than that in the sintered boron-free steels.

Influence of Boron Additions and Heat Treatments on the Fatigue Resistance of CoCrMo Alloys.

Cobalt-based alloys are widely used in the manufacture of joint prostheses. In this study, the effect of boron additions and heat treatment on the ASTM F75 was evaluated by rotating bending fatigue. The boron ranged from 0.06–1 wt %. The alloys were tested in as-cast and heat-treated conditions. In the as-cast condition, the infinite life was observed at 380 MPa, improving to 433–615 MPa according to the amount of boron added. In the heat treatment condition, the fatigue resistance was improved only in the base alloy. The addition of 0.06 wt % boron and heat treatment led to the same resistance as in the as-cast condition. Adding large amounts of boron combined with heat treatment diminished the fatigue limit. The fracture analysis revealed primarily brittle behaviour with some ductile features even on the same sample; only the heat-treated alloy with 0.06 wt % boron was clearly ductile. This alloy also exhibited notably better toughness to crack propagation.

Phase transformations and properties of concentration-inhomogeneous magnetic materials based on the Fe–30%Cr–27%Co system

The phase and structural transformations of a powder magnetically hard alloy of the system Fe–30%Cr–27%Co–1%Si–0,07%B with a metastable α1+α2 phase composition, a high content of cobalt, and a high level of magnetic properties were studied. The density and coefficient of variation of the concentration of the main elements of the sintered blanks at the level of deformable analogs are achieved by sintering in the α-phase with contact melting in the presence of a «vanishing» liquid phase formed due to the addition of silicon and boron ferroalloys. A kinetic approach to the development of a competitive hard magnetic alloy with a high proportion of the strongly magnetic phase is proposed. The effect of boron additions on the incubation period of the formation of an undesirable σ-phase and the temperature range of the concentration stratification of the α-solid solution on the strongly magnetic α1-phase and the weakly magnetic α2-phase were established. Optical microscopy, X-ray phase analysis and differential scanning calorimetry were used to determine temperature and time parameters of heat treatment of the alloy, including hardening, thermomagnetic treatment (TMT) and final aging, providing the required combination of Hc and Br by increasing the stability of the metastable α-phase up to 20 minutes in the interval temperatures of spinodal decomposition α → α1 + α2. The greatest increase in magnetic properties after TMT, observed at the 1st and 2nd steps of final aging, is related to the decomposition of the α-solid solution and the formation of subgrain boundaries. Elements of the obtained structure are characterized by submicron and nanometric sizes, which correlate with the research results on deformable alloys based on the Fe – Cr – Co system. The anisotropic α1+α2-structural state achieved by thermomagnetic treatment provided an increase in the magnetic properties of the studied 30H27KSR powder alloy to 30 % and the squareness coefficient of the magnetic hysteresis loop equal to 0,82 .

Influence of Boron Addition on the Microstructure and the Corrosion Resistance of CoCrMo Alloy

Cobalt-based alloys are extensively used in orthopedic applications for joint replacements due to their wear and corrosion resistance. Corrosion, however, is often associated with fatigue failure in these orthopedic devices. In this study, the effect of boron addition on the corrosion behavior of CoCrMo alloys was studied using linear polarization resistance, potentiodynamic polarization curves, electrochemical impedance spectroscopy, and cyclic voltammetry. The samples were analyzed under as-cast and heat treatment conditions after 21 days of immersion in phosphate-buffered saline (PBS) solution at 37 °C. The boron addition increased the particle content, while the heat treatment promoted enlargement and even distribution of the precipitates throughout the structure. The corrosion resistance was improved by both boron and heat treatments. The best performance was observed for a heat-treated alloy having a very small amount of boron, which had an increased resistance to corrosive attack. Such behavior was attributed to the homogenized microstructure achieved by boron and heat treatment that helped to form a stable passive layer of chromium oxide which endured the 21 days of immersion.

The Effect of Boron Addition on the Microstructure, Hardness and Characteristic Temperatures of Cu-12Al-4Ni Memory Alloy Prepared by Mechanical Alloying, Pressing and Rolling

The Effect of Boron Addition on the Microstructure, Hardness and Characteristic Temperatures of Cu-12Al-4Ni Memory Alloy Prepared by Mechanical Alloying, Pressing and Rolling

Effect of Boron Addition on Liquid Zinc Embrittlement of Heat Affected Zone in 490 MPa Grade Steels

Effect of Boron Addition on Liquid Zinc Embrittlement of Heat Affected Zone in 490 MPa Grade Steels

Effect of boron addition on mechanical properties of Fe-Ni-Mo-B-C sintered alloys

Effect of boron addition on mechanical properties of Fe-Ni-Mo-B-C sintered alloys

Effect of Boron Addition for on Time Temperature Transformation Behavior in Si Added High Carbon Steels

Effect of Boron Addition for on Time Temperature Transformation Behavior in Si Added High Carbon Steels

Effect of boron addition on microstructure, mechanical properties and oxidation resistance of TaC ceramics

TaC ceramics with 0.03–0.60 wt% of boron additions were prepared by hot pressing at 2100 °C for 1 h under a pressure of 40 MPa. Effects of boron content on densification, phase composition, microstructure, mechanical properties and oxidation resistance of the TaC ceramics were investigated. When the boron content was 0.12 wt% and above, full density was obtained due to reactions between boron and oxygen impurity at presence of TaC. Minor phases of TaB2 and C were formed in the 0.24 and 0.60 wt% B compositions after gas-out of the oxygen impurity. Microstructure of the TaC ceramics was refined with increasing in boron content. The TaC ceramic with 0.24 wt% of boron showed the best mechanical properties with a Vickers hardness, flexural strength and fracture toughness of 17.7 GPa, 534 MPa and 4.6 MPa m1/2, respectively. When more boron was added, interfacial bonding of the TaC grains was strengthened causing a decrease in fracture toughness. Oxidation resistance of the TaC ceramics increased with boron content. Particularly, the 0.60 wt% B composition showed a weight gain of 0.0018 g/cm2 after oxidization at 800 °C in air for 3 h.

Effect of boron addition on microstructure and tensile properties of copper modified ultra high strength NiSiCrCoMo steel

Effect of boron addition on microstructure and tensile properties of a copper modified ultra high strength low alloy NiSiCrCoMo steel is investigated in the present study. Base, Cu and Cu + B modified steels were austenitised and quenched, followed by tempering in the temperature range of 200–750 °C. The effect of tempering temperature on tensile properties along with detailed microstructural changes has been evaluated for these steels at tempering temperatures of 200 °C, 650 °C and 750 °C. Boron addition results in delayed recovery of laths and finer lath structure at higher tempering than that due to only Cu addition in base steel. This contributes for higher strain hardening in boron modified steel at high tempering temperature. A compensating effect in strength has been noticed in Cu modified steel; increase in strength due to presence of precipitates is nullified by the formation of equiaxed polygonal ferrite in this steel.

Effect of boron addition on the solidification sequence and microstructure of AlCoCrFeNi alloys

An in-depth analysis of the effect of boron addition on the microstructure of the equiatomic AlCoCrFeNi High Entropy Alloy (HEA) was performed. Alloys with nominal compositions AlCoCrFeNiB0.1 and AlCoCrFeNi were produced and analyzed by multi-scale characterization techniques, including X-ray diffraction, scanning and transmission electron microscopy coupled with TEM-based orientation mapping technique. CALPHAD simulation was carried out to understand the solidification sequence and the phase stability of the studied alloys. The equiatomic AlCoCrFeNi alloy forms a mixture of an Al-Ni rich B2 phase with a Fe-Cr rich body centered cubic (BCC) phase; small face centered cubic (FCC) islands were also observed. The boron addition leads to the formation of needle-like Cr-rich borides with an orthorhombic structure. Moreover, this addition changes considerably the solidification sequence in later stages of the solidification process, resulting in a more complex microstructure.