As a processing technique to change the organization and properties of materials, heat treatment was widely used to strengthen metallic materials. This study examines the impact of varying cooling rates and heat treatment durations on the mechanical properties and microstructure of AlSi10Mg alloys produced through Selective laser melting (SLM). The heat treatment process was Solution Heat Treatment (SHT, 525 °C), and the heat treatment time includes 1 h, 2 h, and 3 h. Cooling methods consist of Refrigerant Cooling (RC), Water Cooling (WC), Air Cooling (AC), Oil Cooling (OC), and Furnace Cooling (FC). As the cooling rate decreases and the heat treatment time increases, the size of the formed Si phase particles varies from small to large, and the distribution deviates from inhomogeneous to homogeneous. In addition, the number of precipitated particles increases and then decreases. To investigate the impact of cooling rates and heat treatment time on the mechanical properties of AlSi10Mg alloys, quasi-static tensile and compression tests were performed. On the other hand, the tensile strength of the heat-treatment samples decreases while the ductility increases, and the Vickers hardness of the samples also decreases with decreasing cooling rate and increasing heat treatment time. The results of the study showed that the cooling rate and heat treatment time of the material had a greater effect on its tensile properties than on its compressive properties. The samples treated at 525 °C - 2 h - AC exhibited the highest tensile and compressive properties. Finally, the analysis of the strengthening mechanism of AlSi10Mg alloys through the presence of Si phase particles of varying sizes was conducted using transmission electron microscopy.

中文翻译：

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冷却速率和热处理时间对选区激光熔化AlSi10Mg合金Si相的影响：显微组织演变和强化机制


热处理作为一种改变材料组织和性能的加工技术，被广泛用于强化金属材料。本研究探讨了不同的冷却速率和热处理持续时间对通过选择性激光熔化 (SLM) 生产的 AlSi10Mg 合金的机械性能和微观结构的影响。热处理工艺为固溶热处理（SHT，525℃），热处理时间包括1h、2h、3h。冷却方式包括制冷剂冷却（RC）、水冷（WC）、空冷（AC）、油冷（OC）和炉冷（FC）。随着冷却速率降低和热处理时间增加，形成的Si相颗粒尺寸由小变大，分布由不均匀变为均匀。另外，析出粒子的数量先增加后减少。为了研究冷却速率和热处理时间对AlSi10Mg合金机械性能的影响，进行了准静态拉伸和压缩试验。另一方面，随着冷却速率的降低和热处理时间的增加，热处理样品的拉伸强度降低，而塑性增加，并且样品的维氏硬度也降低。研究结果表明，材料的冷却速率和热处理时间对其拉伸性能的影响大于对其压缩性能的影响。在 525 °C - 2 h - AC 下处理的样品表现出最高的拉伸和压缩性能。最后，利用透射电子显微镜分析了不同尺寸的 Si 相颗粒的存在对 AlSi10Mg 合金的强化机制。