Microstructure Evolution and Mechanical Property Response of 3D-Printed Scalmalloy with Different Heat-Treatment Times at 325 °C

Abstract

According to the material nature, aluminum alloys are widely applied in aerospace, construction, and automotive applications due to their characteristics of being lightweight, having good formability, and having good corrosion resistance. To further improve the degree of the lightweight quality, introducing a new material with high specific strength and a structure with a lightweight design would be efficient. Scalmalloy (Al-4.49Mg-0.71Sc-0.51Mn-0.27Zr-0.07Fe-0.03Si alloy), which exhibits high specific strength and is made by a 3D printing process with less design limitation, has huge application potential. In this study, the selective laser melting (SLM) process was introduced for sample preparation. Through XRD, EBSD, and TEM, the microstructure of the heat-treated samples at 325 °C with different heat-treatment times was analyzed to evaluate the optimized heat-treatment parameter for 3D printed Scalmalloy. The relationship between the mechanical properties and the variation of precipitation size and volume fraction is discussed in detail in this study.

High-performance aluminum alloy with fully equiaxed grain microstructure fabricated by laser metal deposition

“…1. It can be seen that the typical microstructure of the LMD sample has only one region-an equiaxed grains area, which is in contrast to many other studies where the microstructure of SLM/LMD processed Scalmalloy shows two distinct regions, one with a very fine grained microstructure without any preferential grain orientation, and another region with large columnar grains growing along the temperature gradient [16,28]. In the processes of SLM and LMD, the heat transfer at the bottom of the deposition layer is mainly through the substrate.…”

“…Since the development of Scalmalloy which contains Sc and Zr, SLM [12][13][14][15][16] was applied as the main additive manufacturing method for processing it. SLM uses computer-controlled laser area selection to scan the powder bed to selectively melt the powder particles and solidify them until a part is formed [17,18].…”

“…After ageing treatment, the mechanical properties of Al-Mg-Sc-Zr alloy are improved with a hardness above 110 (HB) and a tensile strength greater than 400MPa. Kuo et al [16] successfully prepared Scalmalloy by SLM and analyzed the microstructure of heat-treated samples at 325°C at different heat-treatment times. It was found that the mechanical properties of Scalmalloy samples, especially the yield stress, is greatly improved from 286.9 MPa to 455.8 MPa.…”

“…The thickness of the LMD deposition layer is in millimeters. The porosity is also lower than that of SLM [16]. Therefore, it is considered a feasible alternative to SLM for larger parts [33].…”

On the Mechanism of Formation of Bimodal Grain Structure in Al–4.5Mg–0.7Sc–0.3Zr Alloy Processed by Laser Powder Bed Fusion

“…Since Spierings et al's studies, there has continuously been a strong research effort on a number of aspects of LPBF of Al-Mg alloys containing various amounts of Sc and/or Zr. [11][12][13][14][15][16][17][18][19][20][21][22][23] Contents of Sc and Zr differ in various studies so that the kinetics of forming Al 3 (Sc,Zr) may differ. In Zhang et al's [11] study using P/v = 0.18 J mm À1 , Al 3 (Sc,Zr) particles up to 90 nm are found in the as-built state.…”