Novel Structural Materials Through Microstructural Control in Liquid Phase Sintering

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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.