Department of Mechanical, Industrial and Manufacturing Engineering, University of Toledo, Toledo, OH, USA.
Marine Additive Manufacturing Centre of Excellence (MAMCE), University of New Brunswick, Fredericton, NB, Canada E3B 5A1.
Micron. 2022 May;156:103246. doi: 10.1016/j.micron.2022.103246. Epub 2022 Mar 17.
A dual-stage indentation test at ambient temperature including a constant indentation load rate followed by a constant indentation load-hold segment was employed to assess the time-dependent plastic deformation of cast and additive manufactured Al-Cu-Mg-Ag-TiB alloys in as-fabricated and T7 conditions at room temperature. Optical microscopy, scanning electron microscopy, electron backscattered diffraction, and transmission electron microscopy techniques were used to study the microstructure of the samples and to correlate the microstructure with the creep properties. That is, the indentation load/displacement/time data from depth-sensing indentation creep were combined with the advanced microstructural assessments to analyze the controlling mechanisms of creep in as-cast, as-built, and T7 samples. Expectedly, the microstructure of samples manufactured by different methods was substantially different in terms of the grain size and the distribution of TiB particles. The θ'', θ' and Ω phase were formed in all heat-treated samples; however, the density of Ω phase was higher in the cast-T7 samples. Distinct microstructure and precipitation density resulted in different indentation-derived properties, both cast and AM samples at T7 condition showed enhanced creep resistance compared to their as-manufactured counterparts. The main controlling mechanism of creep deformation was found to be dislocation creep based on the indentation-derived creep stress exponent values.
采用双阶段压痕试验在环境温度下进行评估，包括恒定压痕载荷率随后是恒定压痕载荷保持段，以评估铸造和增材制造 Al-Cu-Mg-Ag-TiB 合金在室温下的时效状态和制造状态下的时变塑性变形。使用光学显微镜、扫描电子显微镜、电子背散射衍射和透射电子显微镜技术研究样品的微观结构，并将微观结构与蠕变性能相关联。也就是说，从深度感应压痕蠕变获得的压痕载荷/位移/时间数据与先进的微观结构评估相结合，以分析铸造、制造和 T7 样品中蠕变的控制机制。预期的是，不同方法制造的样品的微观结构在晶粒尺寸和 TiB 颗粒的分布方面有很大的不同。所有热处理样品中都形成了 θ''、θ'和 Ω 相；然而，铸造-T7 样品中的 Ω 相密度更高。不同的微观结构和析出密度导致了不同的压痕衍生性能，T7 状态下的铸造和 AM 样品都表现出比其制造状态更高的抗蠕变能力。基于压痕衍生蠕变应力指数值，发现蠕变变形的主要控制机制是位错蠕变。
