Smolej A.,University of Ljubljana |
Skaza B.,University of Ljubljana |
Journal of Materials Engineering and Performance | Year: 2010
This article describes the superplastic behavior of the Al-4.5Mg-0.46Mn-0.44Sc alloy. The investigated alloy was produced by casting and was conventionally processed to form a sheet with a thickness of 1.9 mm and an average grain size of 11 lm. The superplastic properties of the alloy were investigated using a uniaxial tensile testing with a constant cross-head speed and with a constant strain rate in the range 13×10 -4 to 5×10 -2 s -1 at temperatures from 390 to 550 °C. The investigations included determinations of the truestress, true-strain characteristics, the maximum elongations to failure, the strain-rate sensitivity index m, and the microstructure of the alloy. The m-values determined with the strain-rate jump test varied from 0.35 to 0.70 in the temperature interval from 390 to 550°C and strain rates up to 2×10 -2 s -1. The m-values decreased with increased strain during pulling. The elongations to failure were in accordance with the m-values. They increased with the temperature and were over 1000%, up to 1×10 -3 s -1 at 480 °C and up to 1×10 -2 s -1 at 550 °C. A maximum elongation of 1969% was achieved at an initial strain rate of 5×10 -3 s -1 and 550 °C. The results show that the addition of about 0.4 wt.% of Sc to the standard Al-Mg-Mn alloy, fabricated by a conventional manufacturing route, including hot and cold rolling with subsequent recrystallization annealing, results in good superplastic ductility. © ASM International.
Influence of the foaming precursor's composition and density on the foaming efficiency, Microstructure development and mechanical properties of aluminium foams [VPLIV sestave in gostote prekurzorjev za penjenje na učinkovitost penjenja ter razvoj mikrostrukture in mehanskih lastnosti aluminijskih pen]
Kevorkijan V.,Zasebni raziskovalec |
Skapin S.D.,Jozef Stefan Institute |
Paulin I.,Institute Za Kovinske Materiale in Tehnologije |
Sustarsic B.,Institute Za Kovinske Materiale in Tehnologije |
And 2 more authors.
Materiali in Tehnologije | Year: 2011
In this work, the influence of the composition, density and porosity of foaming precursors on the foaming efficiency, microstructure development and mechanical properties of aluminium foams are presented and discussed. The foams were prepared, starting from precursors made either by powder metallurgy (PM) or by the melt route. Following the PM route, precursors were made by mixing Al powder and 3-10 % of volume fractions of dolomite or calcium carbonate particles of particle size from 20 μm to 120 μm and cold isostatically pressing the mixture at 700 MPa. In the case of the melting route, precursors were made by introducing dolomite or calcium carbonate particles directly into the molten aluminium at 700 oC. After melt stirring, the precursors were prepared by casting the semi-solid slurry into a cylindrical, water-cooled mould. Finally, aluminium foams were made in all cases by inserting precursors into a cylindrical stainless-steel mould and heating the arrangement at 750 oC for 10 min. After that, the mould was removed from the furnace and the foaming process was stopped by cooling in air to room temperature. The microstructure of the obtained foams was investigated by optical and scanning electron microscopy (SEM-EDS), while XRD was applied for a detailed identification of phases. The quality of the precursors was evaluated by determining their mechanical properties (uniaxial room-temperature compression stress-strain curve, compressive strength and energy absorption after a 30 % strain) and the foaming efficiency (the relative density of the foam obtained). The concentration of the foaming agent and the density of precursors were found to have a detrimental influence on the foaming efficiency as well as on the foam's microstructure and mechanical properties. The foaming of precursors with open porosity were inefficient.
Volsak D.,Impol |
Voncina M.,University of Ljubljana |
Mrvar P.,University of Ljubljana |
Medved J.,University of Ljubljana
Materiali in Tehnologije | Year: 2012
The effect of a Nd addition on the AlCu5.5BiSn alloy was investigated using thermal analysis, calculations of thermodynamic equilibrium, differential scanning calorimetry (DSC), and optical and scanning electron microscopy (SEM) in order to identify the generated microstructures. The purpose of this study was to analyze the influence of the Nd addition on the AlCu5.5BiSn alloy from the thermodynamics point of view and, consequently, on its mechanical properties. The results show that the Nd addition caused an increase in the eutectic solidification temperature and solidus temperature, which led to a narrower solidification interval. It was also discovered that neodymium formed a binary eutectic (αAl + Al2Cu(Nd)).
Impol | Date: 2003-05-27
Aluminum for use in further manufacture, aluminum alloys for use in further manufacture and aluminum products made by rolling, casting, drawing, and extrusion, namely strips, sheets, plates, circles, foil, castings, profiles, tubes, bars, rods, and non-electrical wires; metal safes; light metals and their alloys for use in further manufacture; aluminum and light metal products made by rolling, casting, drawing, and extrusion, namely, strips, sheets, plates, circles, foil, castings, profiles, tubes, bars, rods, and non-electrical wires; metal foils; sheet metal made of common metals; traffic signs made of common metals; common metal ingots; tubes and non-electrical wires made of common metals. Electrical wires. Mechanical and/or chemical processing or transformation of light metal materials other than buildings; mechanical and/or chemical processing or transformation of aluminum materials other than buildings. Scientific and industrial research for metal processing/transforming industry; scientific and industrial research for light metal industry; scientific and industrial research for aluminum industry; projecting/designing, engineering and technical consulting for metal processing/ transforming industry; engineering and technical consulting for light metal industry; engineering and technical consulting for aluminum industry; technical testing and analysis for metal processing/ transforming industry; technical testing and analysis for light metal industry; technical testing and analysis for aluminum industry; computer programming and consulting for all above-listed fields.
Smolej A.,University of Ljubljana |
Klobear D.,University of Ljubljana |
Skaza B.,University of Ljubljana |
Nagode A.,University of Ljubljana |
And 3 more authors.
International Journal of Materials Research | Year: 2014
The paper describes the effect of minor additions of scandium and zirconium on the superplastic behaviour of friction stir processed Al-5Mg based alloy. The measurements included the flow curves and tensile elongations of (in wt.%) Al-5Mg-0.1Zr, Al-5Mg-0.2Sc, and Al-5Mg-0.2Sc-0.15Zr alloys at initial strain rates ranging from 1 • 10-3 to 1 × 10-1 s-1, and at forming temperatures from 350 to 500 °C. The inclusion of friction stir processing at tool rotation rates of 95 and 475 rpm considerably enhanced the superplastic behaviour of the Al-5Mg-0.2Sc-0.15Zr alloy, which was reflected in elongations without failure of over 1 900 %. Other friction stir processed alloys, treated at lower tool rotation rates, did not achieve superplasticity due to abnormal grain growth. The results yielded by the friction stir processed alloys are compared with the superplastic behaviour of the same alloys produced conventionally by cold rolling.