Microstructures And Properties Study Of Cu-Ce Alloys Under Directional Solidification

R-Cu?R is rare earth element?alloys were widely used due to their good physical and chemical properties,but also be limited to their poor room temperature ductility and toughness.The performance of materials depends on their microstructures.Directional solidification techniques can be used to obtain preferentially oriented structures to improve properties of material.In this study,Cu-Ce series alloys were prepared by high temperature gradient directional solidification technique,the microstructure evolution and related properties at different withdrawal rates were discussed.Six alloys which had different composition were prepared by arc smelting furnace.The eutectic Cu-9%Ce alloy exhibits a pronounced short rod eutectic structure,and the phase composition obtained at room temperature was the same with equilibrium solidification;The eutectic Cu-26%Ce alloy exhibits a lamellar eutectic structure,and the phase composition obtained at room temperature is partially offset from equilibrium solidification.The peritectic Cu₅Ce alloy exhibits a non-equilibrium peritectic structure,and the black primary phase was completely encapsulated by the white peritectic phase.The stable Cu₂Ce phase have obvious defects under OM and SEM.The actual content of Ce was lower than the nominal proportion.The existence of Cu₆Ce phase,Cu₅Ce phase and Cu₂Ce phase verified by XRD in room temperature.Polycrystalline structures with different withdrawal rates were prepared by directional solidification.And the evolution and phase selection of the polycrystalline structures were analyzed.Afterwards,compare the experiment dates with theoretical models in primary dendritic spacing.Demonstrate the conclusion by compressive experiment.The Cu-21%Ce alloy was cellular crystals at 2?m/s and 5?m/s,dendritic crystals at 6?m/s,25?m/s and 100?m/s.The maximum primary dendrite spacing and the maximum compressive force?10.5KN?existed at 6?m/s.The Cu₅Ce phase of ingot transformed into Cu₆Ce phase after directional solidification,and the peak intensity was weakened.The CuCe alloy was cellular crystals below8?m/s,and dendritic crystals at super 10?m/s.The maximum primary dendrite spacing,the maximum compressive force and strain existed at 10?m/s.The peritectic phase of the sample completely separated the primary phase from the matrix.Moreover,the thickness of the peritectic phase gradually thinns with increasing the withdrawal rate.The intensity of Cu₂Ce phase was gradually increased,while the Cu₅Ce phase is gradually weakening.