Structure and Magnetic Properties of Hot Pressed NiFe Powder

The aim of this work is to investigate the structure and magnetic properties of compacted microcrystalline NiFe (81 wt.% of Ni) powder. Bulk samples were prepared by compaction of milled NiFe (81 wt.% of Ni) ribbon. We found that after compaction of the powder displacement of domain walls becomes more dominant and the coercivity decreases and is comparable with the coercivity of conventional permalloy. The coercivity of the bulk material before heat treatment is lower than that for powder and that is why we can assume that the magnetic "contact" is restored after compaction. Annealing of bulk samples reduces the losses due to the relaxation of internal stresses induced by milling and compaction

Implications of the Presence of Y As a Reactive Element in Cathodic Vacuum ARC TiAlN Protective Coating for Tribological Applications

The results of studies of the influence of Y as a reactive element on the properties of TiAlN coatings obtained by the method of vacuum-arc deposition are given. Changes in the structure and properties were analyzed using SEM in combination with EDX, XRD, indentation analysis and wear analysis. It is shown that the presence of Y changes the crystalline phase of the Ti0.6Al0.34Y0.06N coating. It consists of a combination of a cubic NaCl structure (basic phase) and a wurtzite structure (additional phase). In addition, it leads to a small grain size (12 nm) and a nano-columnar structure. The high hardness is partly the result of solution hardening due to the inclusion of larger Y atoms in the TiAlN lattice at the locations of the metal atoms. The reduced grain size of 12 nm also helps to increase the hardness of the coating. The hardness is 31 ± 2.5 GPa, the modulus of elasticity is 394.8 ± 35.8 GPa. The residual stress is approximately three times (−3352 ± 64 MPa) higher than the TiAlN coating (−720 MPa). In addition, a high level of compressive stress contributes to an increase in hardness, since defects responsible for their own compressive stress are an obstacle to dislocation movement. The improved hardness of the experimental coating can be explained by a triple effect: solution strengthening, grain grinding and high residual compressive stress. The addition of Y indicates a slower growth of the oxide layer on the surface of the coating during the wear test. After the addition of Y, Y ions preferentially separate at the grain boundaries and therefore effectively delay the inward diffusion of oxygen. The addition of Y promotes the formation of dense Al2O3, which is effective in restraining diffusion and therefore protects the coating from oxidative wear

Structure and Magnetic Properties of Hot Pressed NiFe Powder

The aim of this work is to investigate the structure and magnetic properties of compacted microcrystalline NiFe (81 wt. % of Ni) powder. Bulk samples were prepared by compaction of milled NiFe (81 wt. % of Ni) ribbon. We found that after compaction of the powder displacement of domain walls becomes more dominant and the coercivity decreases and is comparable with the coercivity of conventional permalloy. The coercivity of the bulk material before heat treatment is lower than that for powder and that is why we can assume that the magnetic "contact" is restored after compaction. Annealing of bulk samples reduces the losses due to the relaxation of internal stresses induced by milling and compaction

Structure and Magnetic Properties of Hot Pressed NiFe Powder

The aim of this work is to investigate the structure and magnetic properties of compacted microcrystalline NiFe (81 wt. % of Ni) powder. Bulk samples were prepared by compaction of milled NiFe (81 wt. % of Ni) ribbon. We found that after compaction of the powder displacement of domain walls becomes more dominant and the coercivity decreases and is comparable with the coercivity of conventional permalloy. The coercivity of the bulk material before heat treatment is lower than that for powder and that is why we can assume that the magnetic "contact" is restored after compaction. Annealing of bulk samples reduces the losses due to the relaxation of internal stresses induced by milling and compaction

Quantitative X-Ray Diffraction Analysis of Zn-Al Based Alloys

The paper describes modification to Fm3 ̅m (space group no. 225) lattice of aluminium based α-solid solution observed in Zn-Al alloys required to properly correlate quantitative data from X-ray diffraction analysis with results obtained from quantitative scanning electron microscopy image analysis and those predicted from Zn-Al binary phase diagram. Results suggests that 14 at.% of Zn as a solute atom should be introduced in crystal lattice of aluminium to obtain correct estimation of phase quantities determined by quantitative X-ray diffraction analysis. It was shown that this modification holds for Cu mould cast as well as annealed and water-cooled samples of Zn-3wt.%. Al and Zn-5wt.% Al

The Influence of the Laser Beam Fluence on Change in Microstructure, Microhardness and Phase Composition of Feb-Fe2B Surface Layers Produced on Vanadis-6 Steel

The paper presents the study results of laser modification of Vanadis-6 steel after diffusion boronized. The influence of laser beam fluence on selected properties was investigated. Diffusion boronizing lead to formation the FeB and Fe2B iron borides. After laser modification the layers were consisted of: remelted zone, heat affected zone and substrate. It was found that increase of laser beam fluence have influence on increase in dimensions of laser tracks. In the thicker remelting zone, the primary dendrites and boron eutectics were detected. In the thinner remelting zone the primary carbo-borides and eutectics were observed. In obtained layers the FeB, Fe2B, Fe3B0.7C0.3 and Cr2B phases were detected. Laser remelting process caused obtained the mild microhardness gradient from the surface to the substrate. In the remelted zone was in the range from 1800 HV0.1 to 1000 HV0.1. It was found that the laser beam fluence equal to 12.7 J/mm2 was most favorable. Using this value, microhardness was relatively high and homogeneous