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Analysis of the Fracture Surfaces of New Development Insulated Iron Powder Compounds

100%
Bidulský R., Bidulská J., Kvačkaj T., Actis Grande M.
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vol. 126
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issue 1
154-155
EN
Goal of the present paper is the analysis of the fracture surfaces of an Insulated Iron Powder Compound (IIPC) with different additions of aluminium alloy (0.25, 0.5 and 0.75 wt.%), in order to improve the mechanical properties, evaluated as the transverse rupture strength (TRS) with sufficient magnetic properties (mainly represented by the iron loss and coercivity force). Investigation of microstructure and porosity development concluded that improvements in bending strength and impact values require the reduction of surface oxides during the heat treatment, in order to get a proper load bearing area between the adjacent particles.
2
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Role of Microstructure Discontinuities in the Soft Magnetic Composites with Aluminium Alloy Addition

100%
Bidulský R., Bidulská J., Actis Grande M.
Archives of Metallurgy and Materials
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2013
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issue 2
3
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Analysis of Densification Process and Structure of PM Al-Mg-Si-Cu-Fe and Al-Zn-Mg-Cu-Sn Alloys

100%
Bidulský R., Bidulská J., Actis Grande M.
Archives of Metallurgy and Materials
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2014
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issue 1
4
Content available remote

The Porosity Evaluation during ECAP in Aluminium PM Alloy

100%
Bidulská J., Kvačkaj T., Bidulský R., Actis Grande M.
Acta Physica Polonica A
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2012
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vol. 122
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issue 3
553-556
EN
The main aim of this paper is to show porosity evolution during application of various processing conditions including pressing, sintering and equal channel angular pressure. An aluminium based powder (Al-Mg-Si-Cu-Fe) was used as investigated material. After applying different pressing pressures (400 and 600 MPa), specimens were dewaxed in a ventilated furnace at 400C for 60 min. Sintering was carried out in a vacuum furnace at 610C for 30 min. The specimens were processed by single equal channel angular pressure pass. A significant disadvantage of powder metallurgy processing methods is the presence of porosity. Pores act as crack initiators and, due to their presence, the distribution of stress is inhomogeneous across the cross-section and leads to reduction of the effective load bearing area. The equal channel angular pressure process, causing stress distribution in deformed specimens, made the powder particles to squeeze together to such an extent that the initially interconnected pores transform to small isolated pores. The proposed safety diagram includes the combined effect of stress and strain behaviour during equal channel angular pressure. The "safety line" eliminates and quantifies the effect of large pores as a potential fracture initiation sites with respect to the mechanical viewpoint.
5
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Correlation between Microstructure/Fracture Surfaces and Material Properties

100%
Bidulský R., Bidulská J., Actis Grande M.
Acta Physica Polonica A
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2012
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vol. 122
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issue 3
548-552
EN
The present paper deals with the evaluation of the effect of different vacuum heat treatments on the microstructure and fracture surfaces of a low alloyed sintered Fe-[1.5Cr-0.2Mo]-0.6C steel, in correlation with the mechanical and plastic properties achieved. The heat treatment consists of the sintering process in vacuum furnace at 1393 K for 1800 s, followed by different cooling conditions and an integrated final tempering at 473 K for 3600 s. The average cooling rates, calculated in the range of 1393 K to 673 K, were 0.1, 0.235, 3, and 6 K/s, respectively. Vacuum heat treatment is supporting the bainitic-martensitic microstructure, the higher the faster cooling rate applied. This provides a marked increase in strength coupled to a decrease in ductility. The decrease of the impact energy after heat treatment is justified by the microstructural changes, especially if a part of bainite is converted to brittle martensite. Samples with bainitic microstructure presented higher impact energies than those with martensitic microstructure. This is fully confirmed by the fracture surface analysis at higher magnification, revealing three main micromechanisms of fracture: brittle, ductile and quasi-cleavage.
6
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Structure Investigation of Ball Milled Composite Powder Based on AlSi5Cu2 Alloy Chips Modified by Sic Particles

88%
Suśniak M., Dutkiewicz J., Rosso M., Karwan-Baczewska J., Actis Grande M.
Archives of Metallurgy and Materials
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2013
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issue 2
7
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Identification of the Critical Pore Sizes in Sintered and Ecaped Aluminium 6XXX Alloy

88%
Bidulská J., Kvačkaj T., Pokorný I., Bidulský R., Actis Grande M.
Archives of Metallurgy and Materials
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2013
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issue 2
8
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The Effects of Chemical Composition on Soft Magnetic Materials Behaviour

88%
Bidulský R., Actis Grande M., Ferraris L., Ferraris P., Bidulská J.
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issue 5
802-803
EN
The main aim of the presented work was to study the effects of chemical composition on the magnetic properties (in terms of B-H characteristics) of an insulated iron powder compound with various addition of the aluminium alloy (0, 5 and 10 wt%). The magnetic properties of the powder were significantly influenced by density and "sintering" effects. The addition of aluminium alloy maintaining suitable values of coercive force, remanence and core losses; this makes the modified insulated iron powder compound a promising soft magnetic material in several applications.
9
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Investigation of Fracture Surfaces of Soft Magnetic Materials

88%
Bidulská J., Kvačkaj T., Bidulský R., Actis Grande M., Ferraris L.
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issue 5
800-801
EN
The present paper focused on the analysis of the fracture surfaces of a new development insulated iron powder compound with the addition of the aluminium alloy in order to improve the mechanical properties. Results show that in the pressed state, mainly pores act as crack initiators and due to their presence the distribution of stress is inhomogeneous across the cross-section and leads to the reduction of the effective load bearing area. Investigation of fracture surfaces concluded that improvements in bonding during the pressing process and heat treatment can be helpful in the development of soft magnetic materials to give a suitable combination between pressing pressure, annealing temperature and time as well as magnetic properties.
10
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An Experimental Study Of Aluminum Alloy Matrix Composite Reinforced SiC Made By Hot Pressing Method

88%
Suśniak M., Dutkiewicz J., Rosso M., Karwan-Baczewska J., Actis Grande M.
Archives of Metallurgy and Materials
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2015
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issue 2
11
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Interparticle Neck Connections in Innovative Insulated Iron Powder Compounds

76%
Bidulský R., Bidulská J., de Oro R., Hryha E., Maccarini M., Forno I., Actis Grande M.
Acta Physica Polonica A
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2015
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vol. 128
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issue 4
647-650
EN
Goal of the present paper is the analysis of the interparticle neck connections in a system made of insulated iron powder compounds with different additions of an Al-Mg-Si-Cu alloy (0.25, 0.5 and 0.75 wt%). The introduction of the aluminium alloy powder has been made in order to improve the mechanical properties, evaluated as the transverse rupture strength, without decreasing the magnetic properties (evaluated in terms of iron loss and coercivity force). The fracture analysis of investigated systems puts into evidence the breaking of interparticle neck connections. Heat treatment (at the temperature of 500°C) contributes to the early stages of interparticle neck developments. The chosen aluminium alloy presents a sort of pre-sintering behaviour at 500°C, with the possibility of mass-transport processes around the insulated iron powder compounds. The air heat treatment applied aims at providing an increase in the mechanical behaviour of the material, with a final good rigidity after the cooling process. Fracture surfaces and transverse rupture strength values show that, at 500 MPa, the strength and the area related to the inter-particle necks can be correlated to the occasional broken insulated point-to-point surfaces that hinder the development of inter-particles necks.
12
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Microdeformation Processes in Soft Magnetic Compounds

76%
Bidulský R., Bidulská J., Petroušek P., Fedoriková A., Dudrová E., Actis Grande M.
Acta Physica Polonica A
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2017
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vol. 131
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issue 5
1367-1370
EN
Porosity can be defined in different ways. The most frequently used definition is the total porosity, which is the total volume fraction of empty space in the specimen. The presence of pores strongly affects the fracture mode. Besides the evaluation of geometry and quality of connections, fractographic analysis enables a quantification of the important microstructural characteristics of the plane porosity. This quantity allows to quantify the existing relations between microstructure and properties. The fractographic evaluation of the distribution of microdeformation processes in the volume of experimental material demonstrates the influence of porosity on the concentration of deformation flows into the microvolume of connections. Plain porosity contributes to the recognition of critical microstructural defects and therefore, to enable evaluating the relationship between the processing parameters, microstructural constituents, and pores. In the fractography evaluation, the analysis of the quality of interparticle bonding using determination of elementary types of fracture facets allows to interpret the mechanical and plastic properties of investigated materials.
13
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Influence of ECAP-Back Pressure on the Porosity Distribution

76%
Bidulská J., Kvačkaj T., Kočiško R., Bidulský R., Actis Grande M., Donič T., Martikán M.
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EN
The main aim of this paper is to show how back pressure equal channel angular pressing (ECAP-BP) influences the porosity distribution in powder metallurgy (PM) aluminium alloys. When back pressure is applied, the accumulation of damage in deformed samples decreases due to the fact that the shear strain takes place under predominantly compressive stresses. Consequently, ECAP-BP influences the porosity distribution in terms of the severe shear deformation involved. According to the obtained results, interesting applications for this new progressive method in physical and metallurgical research fields are shown.
14
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Characterization of Microstructural and Mechanical Properties after Cold Rolling of an Electro-Sinter-Forged Cu-Sn Alloy

72%
Gobber F. S., Bidulská J., Fais A., Franchini F., Bidulský R., Kvačkaj T., Actis Grande M., Gobber F. S., Bidulská J., Fais A., Franchini F., Bidulský R., Kvačkaj T., Actis Grande M.
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