电子束熔丝沉积镍基高温合金组织演变及力学性能研究

Study on the Microstructure Evolution and Mechanical Properties of Nickel-based Superalloy Deposited by Electron Beam Freeform Fabrication

电子束熔丝沉积技术因其材料利用率高、高能量密度和高真空环境等在航空航天等领域得到广泛应用。以GH4169镍基高温合金为研究对象,开展电子束熔丝沉积实验,利用SEM、TEM和XRD等表征手段对显微组织进行分析。同时,在室温下对沉积态试样进行力学性能测试,以研究沉积过程中微观组织演变及其对力学性能的影响。研究发现,沉积过程中元素偏析导致Laves相沿枝晶间析出,热循环引起的热累积导致γ″相在Laves相周围析出。在加载阶段,硬脆的Laves相破碎形成裂纹源,断裂模式为微孔聚集型断裂。

The electron beam freeform fabrication technique has been widely used in aerospace and other fields due to its advantages,such as high material utilization,high energy density and high vacuum environment.Using a GH4169 nickel-based superalloy as the research object,an electron beam freeform fabrication deposition experiment was carried out,and the microstructure was analysed via SEM,TEM and XRD.At the same time,the mechanical properties of the as-deposited sample were tested at room temperature to study the evolution of the microstructure during the deposition process and its influence on the mechanical properties.The results show that the element segregation during the deposition process causes the Laves phase to precipitate along the dendrites,and the heat accumulation caused by thermal cycling results in the precipitation of theγ″phase around the Laves phase.During the loading stage,the hard and brittle Laves phase breaks to form a crack source,and the fracture mode is microvoid coalescence fracture.