Effect of cobalt on the oxidation resistance of Pr(Nd)–Dy–Fe–Co–B materials

The effect of cobalt on the oxidation resistance of (Nd_0.85Dy_0.15)_16.4(Fe_0.89Co_0.11)_74.4Ti_1.3B_7.9 and (Pr_0.56Dy_0.39Sm_0.05)_14.5(Fe_0.75Co_0.25)_78.8B_6.7 alloys has been studied. The storage of magnet blanks made from these alloy in air for 200 h does not affect the magnetic properties of the sintered magnets owing to the presence of the phases (Pr, Dy)(Fe, Co)₂, (Pr, Dy)(Fe, Co)₂B₂, (Pr, Dy)(Fe, Co)₄B, (Pr, Dy)(Fe, Co)₃B₂, and (Pr, Dy)(Fe, Co)₃, which are resistant to oxidation and ensure liquid-phase sintering of magnets. After 200-h exposure to air, oxidation of the blanks takes place, the rate of which decreases by more than two times at the expense of an increase in the cobalt content in the alloy.     

Effect of Annealing of a Pr–Dy–Fe–Co–B Alloy on Its Phase Composition and the Properties of Related Sintered Magnets

The effect of annealing of a (Pr_0.41Ce_0.12Dy_0.47)_13.46(Fe_0.64Co_0.36)_80.3B_6.24 alloy at 1000°C on its microstructure and the properties of sintered magnets made of it has been studied. In the annealed state, the composition of the main magnetic phase (Pr,Dy)₂(Fe,Co)₁₄B changes sharply (dysprosium content changes), the residual induction of the sintered magnets made of the annealed alloy increases by 6%, and the coercive force determined from magnetization increases by 8.5%. The volume content of the main magnetic phase R₂(Fe,Co)₁₄B in sintered magnets (Nb,Dy)–(Fe,Co)–B and (Pr,Dy)–(Fe,Co)–B is found. The content of this phase in neodymium-based magnets is approximately half as much.     

Effect of the sintering temperature and time on the structure and phase composition of temperature stable hard magnetic materials of the REM–Fe–Co–B system

The structure, the phase composition, and the distribution of alloying elements in the structure of temperature stable hard magnetic materials of the REM–Fe–Co–B system (REM = rare-earth metals), which are prepared under different manufacturing conditions, namely, at different sintering temperatures and times, have been studied. The phase composition, the local chemical composition of phases, the volume fraction of pores, and the manufacturing conditions that allow one to prepare the structure ensuring high magnetic properties have been determined.     

Relation between the residual induction and the temperature stability of sintered Nd–Dy–Fe–Co–B magnets

Relation between the temperature coefficient of induction of materials of the Nd–Dy–Fe–Co–B system at temperatures of 20–100°C and their residual induction has been found. It is shown that the residual induction is 0.6 T at the zero temperature coefficient of induction.     

Study of the Effect of Hot－pressing Techniques on the Magnetic Properties of Pr－Fe－B Alloys

ＳｔｕｄｙｏｆｔｈｅＥｆｆｅｃｔｏｆＨｏｔ－ｐｒｅｓｓｉｎｇＴｅｃｈｎｉｑｕｅｓｏｎｔｈｅＭａｇｎｅｔｉｃＰｒｏｐｅｒｔｉｅｓｏｆＰｒ－Ｆｅ－ＢＡｌｌｏｙｓ￥ＹａｎｇＸｉａｎｊｉｎ（杨贤金），ＹａｏＪｉａｘｉｎ（姚家鑫），ＺｈａｏＮａｉｑｉｎ（赵乃勤...     

Effect of the temperature–rate parameters of directional solidification on the structure formation in high-temperature materials

The effect of the temperature gradient and the crystal growth rate on the structure formation in nickel and niobium superalloys is studied under the conditions of the flat, cellular, dendritic, or dendritic–cellular configuration of a solidification front during directional solidification.     

Effect of Microstructure,Strain Rate,and Elevated Temperature on the Compression Property of Fe–Co–Ni–Cr–Zr Alloy

Metallurgical and Materials Transactions A - Eutectic high-entropy alloys with FCC solid solution phase and hard Laves phase can be used as potential structural materials to meet the service...     

Investigating the Possibility of Fabricating Pr2Fe14B/α-Fe Composite Materials by Oxidation of the Pr–Fe–B Alloy in a Fluidized-Bed Jet Mill

Russian Journal of Non-Ferrous Metals - The results of studying the possibility of fabricating the Pr2Fe14B/α-Fe composite materials by oxidation of the Pr–Fe–B alloy in a...     

Effect of powder oxygen content on the microstructure and properties of Co–Cr dental alloys fabricated by selective laser melting

A high oxygen content can lead to metallurgical defects such as holes and microcracks in the products of selective laser melting (SLM) that significantly reduce the density and mechanical properties of a denture. In this study, a batch of a Co–Cr alloy powder was subjected to forced oxidation. SLM was used to prepare specimens from the powder before and after the treatment for the performance tests. The results showed that Co–Cr alloy powders with oxygen contents 184 and 616?ppm could both achieve good shaping of the specimens under identical SLM conditions. There was no significant difference between the specimens in terms of fuselage morphology, microstructure, density, tensile strength, yield strength and hardness. However, the elongation of the alloy synthesised using the higher oxygen content powder was significantly lowered, but still higher than that required by the ASTM F75 Casting Standard of the United States.     

Effect of the solidification and aging conditions on the mechanical properties of Pb–Ca–Sn battery alloys

The influence of the mold temperature on the mechanical properties and the structure of Pb–Ca–Sn battery alloys during their solidification and subsequent aging is studied.     

Effect of Speed on the Tribological Behavior of Fe–Cu–C Based Self Lubricating Composite

In this work, the effect of different speeds on the tribological properties of sintered iron–copper–graphite (Fe–Cu–C) based self lubricating composites have been studied. Fe–Cu–C based self-lubricating composites were prepared by powder metallurgical compaction and sintering method. CaF₂, a solid lubricant in weight percentages of 0, 3, 6, 9 and 12 was added to the base matrix consisting of Fe-2Cu-0.8C. The fabricated samples were tested for friction and wear at a constant load of 10 N and three different speeds of 0.5, 5 and 10 m/s. The surface properties of unworn and worn surfaces were analyzed using optical and scanning electron microscope. The friction and wear test of the composites exhibited decrease in coefficient of friction and increase in wear loss with the increase in speed. The results also revealed different trends in the friction behavior of the developed composites at low (0.5 m/s) and high speeds(5 and 10 m/s). However, at all test speeds, COF of samples with 3, 6 and 9 wt.% was less than the base matrix, and wear loss of 3 wt.% CaF₂ sample was the lowest at all speeds. Ploughing, adhesive and delamination wear were the dominant wear mechanism as revealed by SEM. Based upon the findings, the developed material could be used for low and high speed antifriction applications.     

Tribological properties of the babbit B83–based composite materials fabricated by powder metallurgy

Technological processes are developed to fabricate composite materials based on B83 babbit using hot pressing of a mixture of powders in the presence of a liquid phase. As a result, the structure of the matrix B83 alloy is dispersed, the morphology of intermetallic phases is changed, and reinforcing micro- and nanosized fillers are introduced and uniformly distributed in the matrix. The tribological properties of the synthesized materials are studied. The friction of the B83 babbit + 0.5 wt % MSR + 3 wt % SiC (MSR is modified schungite rock) composite material at high loads is characterized by an increase in the stability coefficient, and the wear resistance of the material increases by a factor of 1.8 as compared to the as-cast alloy at comparable friction coefficients.     

The thermodynamics of the Fe–Co–S ternary system

The thermodynamic properties of the Fe–Co–S ternary system were determined by equilibrating the system with a known sulphur pressure established by using a gas mixture of H₂S/H₂ at 1473, 1548 and 1623 K. The iso-activity contours for Fe and Co were established by application of the Gibbs Duhem equation using Schuhmann’s method for ternary systems. For this purpose a computer program was used to calculate the activities of iron and cobalt. The cobalt activity coefficients in dilute solutions of cobalt in the iron–cobalt–sulphur system, which are of industrial interest, were determined. From the experimental data, the partial heats of solution for iron, cobalt, and sulphur and the integral heats of solution for the Fe–Co–S ternary systems were derived.     

Effect of Co on Microstructure and Interfacial Properties of FeBased Laser Cladding

The coatings consisting of Fe064Ni036 dendrites as matrix and (Fe,Cr)7(C,B)3 interdendritic compounds as reinforcement were fabricated on the medium steel substrate by laser cladding using the Febased powders with different Co content, and Co is uniformly dissolved in the coatings. Compared with the coatings containing 1% and 5% Co, the coating containing 3% Co increases in the area fraction of the interdendritic region by about 5%, in the microhardness nearby the interface by about HV 55 and in the interfacial bond strength by about 30 MPa. The interface fracture morphology exhibits the tear appearance, which can be characterized as the ductile fracture.     

Solidus Surface of the Mo–Fe–B System

Powder Metallurgy and Metal Ceramics - The arc-melted Mo–Fe–B alloys with boron content up to ~41 at.% were studied after annealing at subsolidus temperatures by X-ray diffraction,...     

Effect of Vacuum Hot Pressing Temperature on the Mechanical and Tribological Properties of the Fe–Cu–Ni–Sn–VN Composites

Powder Metallurgy and Metal Ceramics - The mechanical (hardness and elastic modulus) and tribological (friction force and wear rate) properties of the Fe–Cu–Ni–Sn–VN...     

Effect of annealing process on magnetic properties of Sm（Co0.6Fe0.27Cu0.1Zr0.03）7.5 ribbons

Sm(Co0.6Fe0.27Cu0.1Zr0.03)7.5 ribbons were prepared by melt-spun method. The results showed that the remnant magnetization Mr and intrinsic coercivity Hci had a rapid increase when the heating rate increased from 5 to 10℃/min. But the increase of Mr and Hci were observed to be very little when the heating rate was further increased to 20℃/min. 10℃/min was the critical heating rate for obtaining high magnetic properties. The maximum values of Mr and Hci reached 0.70 T and 780.1 kA/m when the annealing temperature and annealing time were optimized to be 800℃ and 1 h, respectively. Proper second-step heat treatment could suppress the decrease of Hci when the cooling rate increased from 0.7 to 5 ℃/min, which could reduce the cooling time effectively.     

Effect of zirconium on the oxygen solubility in liquid nickel and Ni–Fe melts

The oxygen solubility in liquid nickel containing zirconium is studied experimentally for the first time at 1873 K. The equilibrium constants of the reaction of interaction between zirconium and oxygen dissolved in liquid nickel, the interaction parameters characterizing these solutions, and the zirconium activity coefficient in nickel at infinite dilution are found. The equilibrium constants of the reaction of interaction between zirconium and oxygen dissolved in the melt, the Gibbs energy of the reaction of interaction between zirconium and oxygen, and the interaction parameters characterizing these solutions are calculated at 1873 K for a wide composition range of Ni–Fe alloys. The oxygen solubility in various Ni–Fe melts containing zirconium is found at 1873 K. The deoxidizing capacity of zirconium increases as the iron content increases to 30% and decreases at higher iron content in the melt. This can be explained by the fact that an increase in the iron content lead to, on the one hand, a strengthening of the bonding forces of oxygen atoms in a melt and, on the other hand, to a significant weakening of the bonding forces of zirconium atoms with the base metal.