PSI - Issue 74

ScienceDirect Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2025) 000–000 Available online at www.sciencedirect.com Procedia Structural Integrity 74 (2025) 99–105

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© 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of Libor Pantělejev Abstract This study examines the effects of various heat treatments on the microstructure and mechanical properties of the AlSi9Cu3 alloy produced by laser powder bed fusion technology. In addition to conventional T6 treatment, direct aging at 160 °C (T5 treatment ) and annealing at 250 °C, 300 °C, and 350 °C were applied to evaluate thermal stability and precipitation behavior. The as- built microstructure, consisting of α -Al cells surrounded by a continuous network, remained stable up to 250 °C. At 300 °C, the network disintegrated, leading to a significant hardness reduction, resembling the behavior of LPBF AlSi10Mg alloy. The LPBF AlSi9Cu3 alloy in as-built state exhibited a yield strength of 270 MPa, tensile strength of 493 MPa, and elongation of 5.6 %. Direct aging at 160 °C for 10 h promoted precipitation inside α -Al cells and improved strength to 347 MPa (YS) and 520 MPa (UTS), with elongation slightly reduced to 3.9 %. T6 treatment, despite utilizing the precipitation potential of the alloy, did not surpass the strength achieved through direct ageing, underlining the dominant role of the original cellular microstructure. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of Libor Pant ě lejev Keywords : Laser powder bed fusion technology; AlSi9Cu3 alloy; heat treatment; mechanical properties; microstructure 1. Introduction Laser powder bed fusion technology (LPBF) is an additive manufacturing technology that enables the production of geometrically complex and lightweight components, making it highly attractive for the aerospace and automotive industry (Aboulkhair et al. (2019)). Al-Si based alloys, widely used in these industries for their low density Eleventh International Conference on Materials Structure and Micromechanics of Fracture Effects of heat treatment on microstructure and mechanical properties of LPBF AlSi9Cu3 alloy Kristýna Vašáková a *, Jakub Judas a , Jan Čupera a , Libor Pantělejev a , Daniel Koutný a a Brno University of Technology, Faculty of Mechanical Engineering, Technická 2896/2, Brno 616 69, Czech Republic

* Corresponding author. Tel.: +420 541143166 E-mail address: Kristyna.Vasakova@vutbr.cz

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of Libor Pantělejev 10.1016/j.prostr.2025.10.040 2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of Libor Pant ě lejev