Incorporation of Y2O3 Particles into 410L Stainless Steel by a Powder Metallurgy Route

Addition of yttria to steels has been proposed for the fabrication of oxide-dispersion-strengthened materials for nuclear power applications. We have investigated materials prepared from 12 Cr martensitic stainless steel, AISI 410L, produced by powder metallurgy. Materials were produced with and without yttria addition, and two different sizes of yttria were used, 0.9 µm and 50 nm. Tensile and mini-creep tests were performed to determine mechanical properties. Optical microscopy, SEM, TEM, and EDX analysis were used to investigate the microstructures and deformation mechanisms and to obtain information about non-metallic inclusion particles. SiO2, MnS, and Y2Si2O7 inclusion particles were observed. An SiO2 and Y2O3 interaction was seen to have occurred during the ball milling, which impaired the final mechanical properties. Small-angle neutron scattering experiments showed that the matrix chemistry prevented effective dissolution of the yttria. © The Author(s) 201

Imaging of Magnetic Domains and Domain Walls in Spherical Fe-Si Powder Using Magnetic Force Microscopy

The commercial Fe-Si powder, produced by Högänes Corporation, represents promising soft magnetic material for technological applications. The powder consists of spherical particles with diameter up to 150 μm. Internal microstructure of the powder is formed by grains of diameter of about 30 μm. Each separate grain has a random orientation of the easy magnetization axis and is sufficiently large to split into several magnetic domains. A comparative study of the atomic force microscopy (AFM) topography and the corresponding magnetic force microscopy (MFM) images was employed in order to examine the correlation between the grain size, boundaries of grains and characterization of the magnetic domains, which gives us an important knowledge about possible behavior of particles under the influence of the external magnetic field and further utilization of the spherical Fe-Si particles in electrotechnical industry. The grain size and the crystallographic orientation of grains were analyzed by the electron backscattering diffraction (EBSD) technique

FeSiBAlNiMo High Entropy Alloy Prepared by Mechanical Alloying

High-entropy alloys have attracted increasing attentions because of their unique compositions, microstructures, and adjustable mechanical and functional properties. In this work, mechanical and magnetic properties of the FeSiBAlNiMo high-entropy alloy were studied in heat-treated conditions. Influence of temperature and time of sintering was investigated. The lowest coercivity H_c=370 A/m was reached at sintering temperature 580°C, during 20 min in Ar/10H₂ atmosphere. Resistivity decreases from R=0.006 Ωcm at 580°C of sintering temperature to R=0.0004 Ωcm at temperature 1100°C. Transverse rupture strength TRS = 340 MPa as well as the Young modulus E=87 GPa were much higher in the case of sintering at 1100°C in comparison to TRS = 5 MPa and E=7.5 GPa at sintering temperature 580°C. Low temperature consolidation made possible to structure recovery and stress relief of amorphous-nanocrystalline structure. Higher temperature above 1100°C induced sintering processes and formation of complex borides

FeSiBAlNiMo High Entropy Alloy Prepared by Mechanical Alloying

High-entropy alloys have attracted increasing attentions because of their unique compositions, microstructures, and adjustable mechanical and functional properties. In this work, mechanical and magnetic properties of the FeSiBAlNiMo high-entropy alloy were studied in heat-treated conditions. Influence of temperature and time of sintering was investigated. The lowest coercivity H_c=370 A/m was reached at sintering temperature 580°C, during 20 min in Ar/10H₂ atmosphere. Resistivity decreases from R=0.006 Ωcm at 580°C of sintering temperature to R=0.0004 Ωcm at temperature 1100°C. Transverse rupture strength TRS = 340 MPa as well as the Young modulus E=87 GPa were much higher in the case of sintering at 1100°C in comparison to TRS = 5 MPa and E=7.5 GPa at sintering temperature 580°C. Low temperature consolidation made possible to structure recovery and stress relief of amorphous-nanocrystalline structure. Higher temperature above 1100°C induced sintering processes and formation of complex borides

The influence of NiZnFe₂O₄ content on magnetic properties of supermalloy type material

Soft magnetic composites represent a remarkable kind of materials with wide variety of use. Magnetic properties are dependent on the materials composition and also on the method of preparation. Ni-Fe-Mo alloys (supermalloy) have high complex permeability and low eddy current losses. Soft magnetic NiZnFe₂O₄ ferrites have low coercivity and intermediate saturation magnetization. The Ni_{80}Fe_{14.7}Mo_{4.5}Mn_{0.5}Si_{0.3} (wt%) powder sample was prepared by mechanical alloying of the chemical elements for 24 h. Ni_{0.3}Zn_{0.7}Fe₂O₄ ferrite is commercially available by Sigma Aldrich. Both powders were mixed at selected ratio and uniaxially compacted at 800 MPa. In this paper, we report the experimental observations of the effects of Ni_{0.3}Zn_{0.7}Fe₂O₄ content on the electromagnetic properties of NiFeMoMnSi/Ni_{0.3}Zn_{0.7}Fe₂O₄. The samples contained 5, 10, and 15% of Ni_{0.3}Zn_{0.7}Fe₂O₄ ferrite and were sintered for 30 min at 800°C. An addition of Ni_{0.3}Zn_{0.7}Fe₂O₄ ferrite caused decrease of complex permeability and increase coercivity of the samples. The 5% of Ni_{0.3}Zn_{0.7}Fe₂O₄ sample exhibits the highest value of the real part of complex permeability (48 at 1 kHz). The 10% of Ni_{0.3}Zn_{0.7}Fe₂O₄ sample showed the lowest total magnetic losses