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Carbide nucleation, growth and trapping behavior in directionally solIdified MAR-M247 LC alloyand the corresponding mechanism have been investigated. Carbide forming element enrichmentcontrols the carbide nucleation and the carbide growth behavior. If the carbide forming elementenrichment and the nucleation sites are suitable, carbide nucleation can occur both above andbelow the liquidus temperature. Heterogeneous carbide nucleation is the preferred nucleationmechanism at low carbide forming element enrichment. Carbide growth occurs mainIy at inter-secondary ry dendrite arm area and lower part of the mushy zone. The carbides are subsequentlytrapped at these positions after growing to a certain size. Some carbides are only partially trappedby the solid-liquid interface and the carbide growth accelerates after being partially trapped. Acritical growth rate exists between 2×10-6 m/s and 5 ×10-6 m/s. The carbide volume fractiondecreases in the directionally solidified part at slow growth rate that is caused by the lack ofsuitable growth site and the low trapping ability of the solid-liquid interface
Carbide nucleation, growth and trapping behavior in directionally solIdified MAR-M247 LC alloy and the corresponding mechanism have been investigated. Carbide forming element enrichment control of the carbide nucleation and the carbide growth behavior. If the carbide forming elementenrichment and the nucleation sites are suitable, carbide nucleation can occurs both above and below the liquidus temperature. Heterogeneous carbide nucleation is the preferred nucleation mechanism of low carbide forming element enrichment. Carbide growth occurs mainIy at inter-secondary ry dendrite arm area and lower part of the mushy zone. The carbides are subsequentlytrapped at these positions after Some carbides are only partially trapped by the solid-liquid interface and the carbide growth accelerates after being partially trapped. Acritical growth rate exists between 2 × 10-6 m / s and 5 × 10-6 m / s. The carbide volume fractiondecreases in the directionally solidified part at slow growth rate that is caused by the lack ofsuitable growth site and the low trapping ability of the solid-liquid interface