Abstract
This work investigates the thermal conductivity of parts which have been additively manufactured using the aluminium alloy AlSi10Mg by selective laser melting, a laser-based powder bed fusion technique. Thermal conductivity characterisation is of particular importance to thermal engineers wishing to make use of additive manufacturing in next generation thermal management solutions.A number of processing parameters and scanning strategies were employed to fabricate samples for experimental characterisation. While the porosity of produced parts had a significant impact on thermal conductivity, after an anneal heat treatment post-processing step, thermal conductivity increased by 18–41% without any measurable change in porosity. Even though the parts produced with the “points” strategy have higher levels of porosity compared to the “contour-hatch” strategy, it has been found that after the heat treatment step, its thermal conductivity can be increased up to the “contour-hatch” strategy. Analysis of the resulting microstructures using scanning electron microscope and energy-dispersive X-ray showed precipitation and coalescence of Si with increasing heat treatment temperature, with dwell time having a lower impact.While there is a desire for additively manufactured parts with little to no porosity, it has been shown in this study that it is possible to reduce laser energy density requirements by approximately one order of magnitude and still produce parts with acceptable levels of thermal conductivity which could be used for components that are not subjected to strenuous loading conditions, such as heat sinks.
Highlights
The additive manufacturing (AM) laser-based powder bed fusion process of selective laser melting (SLM) has become a subject of intense research over the past two decades
In order to first verify the efficacy of the experimental thermal conductivity measurement setup outlined in Section 2.3, a number of samples of known thermal conductivity were measured
The average uncertainty values for k and φ are 3.1% and 13.7% respectively. This suggests that the SLM processing param eters control the level of porosity found in AM parts, in line with the results reported by Maskery et al [9]
Summary
The additive manufacturing (AM) laser-based powder bed fusion process of selective laser melting (SLM) has become a subject of intense research over the past two decades. In the review by Frazier [1], it has been described as a important emerging commercial manufacturing technology, with the potential to provide customised parts on demand when and where they are needed. Compared to conventional manufacturing methods for metals, such as casting or machining, AM methods allow for the production of complex shapes with an uncon strained level of design freedom. AM has found uses in a wide range of industries, in aerospace, automotive and for biomedical applications. In the case of the aerospace industry, Liu et al [3] outlines how it is becoming to be of strategic importance as it allows for rapid prototyping, direct manufacture, and repair of components. Mullen et al [4] describes how AM orthopedic parts have been shown to have significant advan tages as they can be made to more closely mimic natural bone structures
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