Thermal Properties of Selectively Laser-Melted AlSi10Mg Products with Different Densities
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JMEPEG https://doi.org/10.1007/s11665-020-05192-z
Thermal Properties of Selectively Laser-Melted AlSi10Mg Products with Different Densities David Martı´nez-Maradiaga, Oleg V. Mishin, and Kurt Engelbrecht (Submitted February 23, 2020; in revised form August 26, 2020; Accepted September 23, 2020) The thermal diffusivity and thermal conductivity of selectively laser-melted AlSi10Mg samples with different target relative densities, 99 and 99.5%, have been studied in the temperature range from 25 to 400 °C. The properties were measured in the build direction and orthogonal to the build direction, for the samples in the as-built and heat-treated conditions. The 99.5% dense samples are characterized by a noticeably higher thermal diffusivity and higher thermal conductivity than the 99% dense samples. For each sample, it is found that the applied heat treatment improves the thermal diffusivity and thermal conductivity of the as-built material, but also results in pronounced anisotropy, with greater thermal diffusivity and conductivity in the build direction, especially for the 99.5% dense sample. The anisotropy is attributed to the presence of Si particles along the grain boundaries of columnar grains. Since the columnar grains are elongated along the build direction, a smaller spacing between particle-decorated boundaries in the plane perpendicular to the build direction presents a higher resistance to the heat conduction. Keywords
AlSi10Mg, additive manufacturing, electron microscopy, microstructure, selective laser melting, thermal properties
1. Introduction Selective laser melting (SLM) is an additive manufacturing technique, in which the material feedstock is deposited layer by layer. In this technique, a laser melts part of the powder in each layer according to the design. Repeated melting and rapid solidification of the material occur during SLM, which results in characteristic microstructures and distinct mechanical properties (Ref 1, 2). The principal advantage of additive manufacturing over conventional methods is the complete design freedom that allows fabricating very complex and intricate geometries. The advances in SLM make it possible to produce parts with reduced weight, increased functionality, or even reduced number of parts in a component. Aluminum alloys such as AlSi10Mg and similar compositions have been extensively used in the SLM process, where the major production challenges include porosity and cracking (Ref 3). Nevertheless, AlSi10Mg and AlSi7Mg0.3 parts with a relative density of 99.8% can be produced by SLM (Ref 4, 5). Since aluminum alloys have a relatively low density, high thermal conductivity, and good corrosion resistance, among other properties, these alloys can be used in a wide range of applications, including heat exchangers and thermal management.
David Martı´nez-Maradiaga and Kurt Engelbrecht, Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark; and Oleg V. Mishin, Department of Mechanical Engineering, Technical University of Denm
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