Novel Structural Materials Through Microstructural Control in Liquid Phase Sintering

本文研究了超固液相烧结（SLPS）过程中的显微组织演变。这是一种粉末金属的致密化技术，其中液体沿着晶界形成，导致颗粒解体，毛细诱导的晶粒重排和溶液再沉淀。包括考虑液体流动的性质和与初始颗粒组成、冷却速度和微观结构有关的颗粒解体机制。工艺变量包括温度、粒度、加热速率和预烧结退火。影响烧结性能的因素包括润湿、孔隙填充、液膜迁移和致密化。几种表征技术（光学和电子显微镜，膨胀测量和差热分析被用来研究微观结构的演变和加工变量的影响）。显示重要参数的烧结图是研究的成果。该工艺可提供高质量零件的近净形成形能力。潜在的应用包括汽轮机叶片、发动机部件和工具钢。

This proposal examines microstructural evolution during supersolidus liquid phase sintering (SLPS). This is a densification technique for powdered metals in which liquid forms along grain boundaries causing particle disintegration, capillary- induced rearrangement of grains, and solution reprecipitation. Included are considerations of the nature of liquid flow and the particle disintegration mechanism related to initial particle composition, cooling rate, and microstructure. Process variables include temperature, particle size, heating rate, and pre-sinter annealing. Factors affecting the sintering behavior include wetting, pore filling, liquid film migration, and compact densification. Several characterization techniques (optical and electron microscopy, dilatometry, and differential thermal analysis are employed to study the microstructural evolution and influence of processing variables). Sintering maps that show the significant parameters are an output of the research. %%% This process offers near net-shape forming capability for high quality parts. Potential applications include steam turbine blades, engine components, and tool steels.