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Fe40Al intermetallic samples sintered by pressure-assisted induction sintering (PAIS) method

  Low density, high specific strength, high specific stiffness and enhanced resistance to wear, corrosion of FeAl alloys in comparison to steels and nickel-based alloys make them attractive for industrial usage [1, 2]. The mechanical properties of FeAl alloys highly depends on the aluminum content. For example, the yield strengths increase with the increase in aluminum content up to 40 at. % Al [2]. Casting is a traditional method of high-aluminum Fe-Al alloys manufacturing. However, during the sintering of Fe-Al alloys from elemental powders strong exothermic reactions (Self propagating High temperature Synthesis - SHS) take place [3]. This phenomenon is utilized during reactive casting named the Exo-melt™. Sikka et al. and Deevi et al. [4÷6] used the exothermic energy generated in SHS reaction to melt different intermetallics for casting. Another method of Fe-Al alloys fabrication is powder metallurgy (PM). Specimens obtain by the PM method possess desired geometry, satisfactory mechanical properties and density close to theoretical. In the present work, Fe40Al sinters were fabricated from elemental powders. The pressure-assisted induction sintering (PAIS) method was used to sinter the specimens. The PAIS apparatus was built at the Department of Advanced Materials and Technology of the Military University of Technology and designed for the production of massive sinters. APPARATUS Scheme and an overview of the apparatus for the PAIS is shown in Figures 1 and 2. The de[...]

The influence of heating rate during sintering on mechanical properties of Fe40Al sinters at room temperature DOI:10.15199/28.2016.5.11

  The results of a uniaxial compression test of Fe40Al (at. %) sintered powders are presented. Compression yield stress Rc0.2, ultimate strength Rcm, permanent deformation, and true compression strength at the maximum force point were determined. All Fe40Al sinters behaved like a plastic material; they were not brittle, and the sample after the compression test did not fall apart and was barrel-shaped. Observations of the microstructure revealed plastically-deformed grains. The obtained sinters were characterized by very high ultimate compressive strength (ok. 2700÷2800 MPa) and low yield stress (Rc0.2 approx. 280 MPa). This paper presents also XRD analyses, microstructure, and density of Fe40Al sinters. Key words: intermetallic alloys, iron aluminides, reaction synthesis, compression test, plasticity.1. INTRODUCTION Despite its obvious advantages, such as low density, good corrosion and oxidation resistance, and high strength at both room and elevated temperature [1÷3], the FeAl-based alloys are still only potentially used as replacements for expensive alloy steels; this is primarily due to their ductility and inherently low toughness, especially at ambient temperature [4]. It is generally known that the mechanical properties of iron aluminides are very sensitive to many factors, including aluminium content, order, heat treatment, the test temperature, alloying additions, environment, microstructure, and defects [5]. Due to the fragility of Fe-Al alloys, which increases with increasing aluminium content, alloys with an aluminium content of 40% are the most frequently analysed. FeAl alloys of 40% Al are characterized by high strength properties at an acceptable ductility. Due to the potential embrittlement of sintered FeAl powders, it is tested mostly by the compression test. Literature sources indicate that the yield stress of Fe40Al at ambient temperature ranges from 380 to 820 MPa [4, 6÷9]. The strain obtained during testing strength[...]

Functionally graded W-Cu composites produced by the Pulse Plasma Sintering method

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The paper presents the results of studies on the fabrication of functionally graded W-Cu composites using the Pulse Plasma Sintering (PPS) method. The functionally graded composites were produced during a single technological process, by sintering powder mixtures with various W/Cu proportions, arranged in consecutive layers. The technological process and the microstructures of the materials [...]

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