研究目的
Investigating the microstructure evolution during laser metal powder directed energy deposition of Alloy 718 and subsequent heat treatments using phase-field modelling and transformation kinetics calculations.
研究成果
The study demonstrated that phase-field modelling combined with transformation kinetics can effectively predict microstructure evolution during LMPDED and subsequent heat treatments of Alloy 718. Elemental segregation was found to significantly influence precipitation kinetics and phase formation.
研究不足
The model resolution was not sufficient to model the precipitation of γ'/γ''. The alloy system was simplified to reduce computational effort, potentially affecting the accuracy of predictions regarding Laves phase composition.
1：Experimental Design and Method Selection
A multi-component and multi-phase-field modelling approach was used to simulate microstructure evolution. The phase-field software MICRESS was utilized for simulations, incorporating thermodynamic and mobility data from TCNI8 and MOBNI4 databases.
2：Sample Selection and Data Sources
Gas atomized Alloy 718 powder was deposited onto an as-cast Alloy 718 substrate. Temperature measurements were made using type-K thermocouples.
3：List of Experimental Equipment and Materials
6kW Ytterbium fibre laser, IRB-4400 ABB Robot, Zeiss EVO 50 Scanning Electron Microscope, Vickers micro-hardness testing machine.
4：Experimental Procedures and Operational Workflow
Single-wall samples with varying layers were deposited. Heat treatment was performed according to a specific protocol. Microstructure evaluation was conducted post-treatment.
5：Data Analysis Methods
SEM images were analyzed using ImageJ. Microhardness measurements were performed to assess mechanical properties.
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