(1. 山东大学 材料液固结构演变与加工教育部重点实验室，济南 250061；
2. 山东大学 材料科学与工程学院，济南 250061)
摘 要: 本文首先制备了含有1.5%(质量分数)TiC的2024铝合金粉末，并将其加入AlSi10Mg合金粉末中，形成AlSi10Mg-2024(TiC)混合粉末，然后采用激光选区熔化工艺对混合粉末成形，并对其沉积态和T6热处理态的显微组织及力学性能进行了表征。结果表明：激光选区熔化过程中2024铝合金中的TiC颗粒可作为异质形核点，促进Al形核，进而抑制粗大柱状晶的形成，显著细化铝合金的显微组织，并弱化了〈100〉//BD(Build direction, 生长方向)丝织构的形成。经过T6热处理(520 ℃固溶2 h，190 ℃时效10 h)后，AlSi10Mg-2024(TiC)合金仍保持较高的力学性能，抗拉强度达到400 MPa。而经T6热处理后AlSi10Mg合金的强度仅为260 MPa。这是因为添加2024合金可以引入Cu元素，在时效过程中析出第二相粒子，强化铝合金基体。另外，时效过程中析出的纳米Si颗粒也可对T6热处理后的AlSi10Mg-2024(TiC)合金起到一定强化作用。
关键字: 激光选区熔化；增材制造；铝合金；AlSi10Mg；2024铝合金
（1. Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan 250061, China;
2. School of Materials Science and Engineering, Shandong University, Jinan 250061, China）
Abstract:In this work, 2024 alloy powders with 1.5% (mass fraction) TiC nanoparticles were produced first. The special 2024(TiC) alloy powders were added into the widely used AlSi10Mg powders through mechanical mixing. Selective laser melting technique was used to fabricated the samples. The microstructure and mechanical properties of the as-fabricated samples and the samples after T6 heat treatment (solution treated at 520 ℃ for 2 h, aging at 190 ℃ for 10 h) were studied. The results show that the TiC nanoparticles could act as the heterogeneous nucleation site of Al grains, leading to the suppression of coarse columnar grains. As a result, the microstructure could be refined remarkably. Moreover, the strong 〈100〉//BD (Build direction) fiber texture is suppressed largely. After T6 heat treatment, the strength of AlSi10Mg alloy drops to 260 MPa, while the strength of 2024(TiC) modified alloy, i.e. AlSi10Mg-2024(TiC) alloy, maintains at a high level of around 400 MPa. This is because the addition of 2024 alloy will introduce Cu element, which promotes the formation of second-phase particles during subsequent aging treatment, and thus strengthening the aluminum matrix. Moreover, the precipitation of nanoscale Si particles may also help to strengthen the T6-treated AlSi10Mg-2024(TiC) alloy.
Key words: selective laser melting; additive manufacturing; aluminum alloy; AlSi10Mg; 2024 alloy
