Key Engineering Materials Vol. 641

Abstract: Experiments on Al-1Fe-1Ni-5Mg alloy were performed to determine the effect of rapid solidification (RS) on the material strengthening, which result from the refining of the grain size and intermetallic compounds. Additionally, an enhancement of the material strengthening due to magnesium addition was also observed. RS procedure was performed using spray deposition of the molten alloy on the rotating water-cooled copper roll. As a result, highly refined structure of rapidly solidified flakes was obtained. Using common powder metallurgy (PM) techniques, i.e. cold pressing, vacuum degassing and hot extrusion, as received RS-flakes were consolidated to the bulk PM materials. For comparison purposes, the conventionally cast and hot extruded Al-1Fe-1Ni-5Mg alloy was studied as well. RS process combined with hot pressing and extrusion procedure was found to be very effective method for the manufacture of fine grained material and effective refinement of intermetallic compounds. However some inhomogenity of particles distribution was observed, which was ascribed to varied cooling rate dependent on the particular spray-drop size. Mechanical properties of as-extruded material were examined using compression test at 293K – 873K. High strength and ductility of as-extruded RS material with respect to conventionally produced alloy were observed. However, the effect of enhanced mechanical properties of RS material is observed only at low deformation temperatures. It was found that increasing deformation temperature above 400K results in negligible hardening of RS samples if compared to conventionally produced material.

Abstract: A mechanical alloying and hot extrusion method was used to manufacture an AlMg-based composite reinforced by ~9 wt.% addition of CeO₂. Structural features of as-extruded and re-melted samples were characterized by SEM/TEM observations and XRD analysis. Highly refined structure with uniform distribution of structural components has been received. It was found that during mechanical alloying and following hot pressing and extrusion of the material the decomposition of CeO₂ oxides has been initiated. As result, formation of intermetallic grains of Al₄Ce type was observed. Thermal analysis experiments combined with structural characterization allowed to determine the equilibrium state of the AlMg-CeO₂ composite structure.

Abstract: Ultra-fine grained metallic materials are characterized by higher mechanical properties comparing with their conventional equivalents. However increase in strength under static load is not always accompanied by improved fatigue behaviour. Previous investigations on submicrocrystalline RS442 aluminium alloy produced by plastic consolidation of rapidly solidified flakes in the extrusion process revealed increase in its high cycle fatigue bending strength caused by annealing at 450°C. The aim of present studies was to evaluate the influence of heat treatment – also precipitation hardening – on static mechanical properties (hardness, tensile and yield strength) and fatigue strength of the alloy determined in high cycle stress controlled bending tests. Correlation between microstructure, static mechanical properties and fatigue behaviour was analyzed too.

Abstract: In this work, hot extrusion of light metal scraps as a new way of plastic consolidation will be presented. This kind of material recovering is a promising alternative for conventional recycling processes. Nowadays discards from machining of semi-finished products are being recycled throughout re-melting processes. However, due to its significant susceptibility to oxidation most of the chips and scraps are burnt during the melting process. It has been already recognized that aluminum losses connected with this operation can reach from 40% to 50%. A technology that has been presented in this work combines cold compaction and hot extrusion of 413.0 aluminum alloy scraps. It was found that quality of as-extruded rods depends strongly on extrusion conditions. Higher extrusion speed leads to higher quality of rods surface. Additionally brittle Si and Al-Fe-Si particles increases overall mechanical properties in comparison to its industrial counterpart.

Abstract: AlSi5Cu2 alloy matrix composite have been studied by microscopic examination and basic tribological properties was evaluated. Composite material was produced by the mechanical milling and spark plasma sintering technique. After sintering process SiC particles were uniformly distributed in the matrix. The wear and the friction coefficients were determinate as a function of the SiC volume fraction. The addition of SiC wt. % had significant effect on tribological properties of that composites. The increase in reinforcement content improves the wear resistance of obtained materials.

Abstract: To make the most of unique properties of diamond and to diminish an influence its disadvantageous properties new diamond tool composites with ceramic bonding phase (MAX) has been proposed. Ti₃(Si,Ge)C₂ and Ti₃SiC₂ were produced by self-propagating high temperature synthesis (SHS). 3-6 µm (MDA, De Beers) diamond powder was mechanically mixed with 10 wt% Ti₃(Si,Ge)C₂ or 30 wt% Ti₃SiC₂, pressed and the compacts were sintered at 1962 °C at 8.0 GPa in a Bridgman-type high pressure apparatus. These mechanical properties were determined: Vickers hardness HV1, Young’s modulus, tensile strength, fracture toughness and wear resistance. Microstructure and phase composition were studied by scanning and transmission electron microscopy and X-ray and electron diffraction techniques. To improve the final quality of the AlCu4MgSi(A) alloy, balls of diamond-new composites were incorporated into the burnishing tools. The influence of burnishing parameters, such as burnishing force and feed, on surface geometry parameters were measured and profilograms of the surface roughness recorded.

Abstract: The discussed subject matter concerns the influence of two kinds of Al-Zr alloy production technologies on the properties of the wires dedicated for electrical purposes. The paper presents research and the analysis of the research into the influence of the production technology and the processing technology on the ingot wires made from the heat resistant Al-Zr alloys as well as on the characteristics of the properties of the examined materials with the focus on the electrical and mechanical properties and their microstructure analysis. The materials subject to the mechanical and physicochemical research were materials manufactured in industrial and laboratory conditions in the form of the wire rod and cast bars as well as wires of various diameters drawn from them. The research concerned six Al-Zr alloys with the zirconium content from 0.05 to 0.32% of the mass.

Abstract: The effect of iron addition on the structure and properties of aluminium wire rod obtained in the laboratory horizontal direct chill casting process has been analyzed. In addition, the impact of the casting speed on the properties of aluminium bars, containing the 0.5 wt% of Fe, and laboratory wire drawing process has been examined. The addition of iron increase the strength and plasticity of aluminium wire rod in as-cast condition and after wire drawing process, while the electrical conductivity drop acceptable. Moreover, by improving the plasticity of wires became possible to increase the deformability limit, measured by the reduction in the wire diameter by drawing to a level of less than 0.5 mm. Small-diameter wires are used for the construction of automotive wire harnesses, cables battery or winding wires. It has been shown that iron is beneficial for mechanical and technological properties of aluminium, and the horizontal direct chill casting process by graphite crystallizer may be an alternative solution in comparison with industrial scale of continuous casting and rolling by Properzi method (CCR) or Southwire SCR process in the context of the preparation of smaller amounts of material with scrap metals.

Abstract: The continuous development of manufacturing processes and techniques in the production of cast aluminum alloy products is possible due to research into casting materials and technologies as well as analyses of the impact of technological factors on the operational parameters of products. A novelty of recent years are the aluminum casting alloys, which are used for carrying electric power in high-voltage Gas Insulated Switchgears - GIS and in elements of hardware for transmission and distribution lines. Casting aluminum alloys occurring in the European standardization are primarily intended for mechanical application and, for this reason, the value of their electrical conductivity is generally omitted or given only for indication. Therefore, there is a justification for undertaking research into the development requirements for the group of alloys, for which electrical properties will be the primary criterion for qualitative acceptance. Hence, the aim of this work is to determine optimal addition of magnesium and heat treatment parameters of AlSi7Mg aluminum cast alloys, in order to achieve the most favorable set of electrical and mechanical properties.