Composition design method of a nickel-based single crystal superalloy seed crystal alloy and nickel-based single crystal superalloy seed crystal alloy

Abstract

The invention provides a composition design method of a nickel-based single crystal superalloy seed crystal alloy and a nickel-based single crystal superalloy seed crystal alloy, which belong to the technical field of single crystal superalloy preparation. The nickel-based single crystal superalloy seed crystal alloy obtained by the composition design method of the present invention can maintain a high degree of matching with the master alloy of the nickel-based single crystal superalloy, so that the difference between the two lattice constants does not exceed 1.5%. The dendrite spacing between the seed crystal of the nickel-based superalloy and the single crystal alloy it grows under the same temperature gradient does not exceed 50 μm, which can reduce the interface energy between the seed crystal and the single crystal master alloy, and reduce the concentration of each element in the single crystal. The segregation between dendrites effectively improves the seed crystal epitaxial growth rate and the compactness and uniformity of the single crystal superalloy structure; the liquidus temperature of the nickel-based single crystal superalloy seed crystal alloy and the master alloy prepared by the present invention The difference does not exceed 20°C, which effectively reduces the miscellaneous crystals produced by the remelting of the seed crystal, thereby preventing the probability of single crystal preparation failure or orientation deviation.

Description

technical field [0001] The invention relates to the technical field of single crystal superalloy preparation, in particular to a composition design method of a nickel-based single crystal superalloy seed crystal alloy and a nickel-based single crystal superalloy seed crystal alloy. Background technique [0002] Due to the continuous increase in the inlet temperature of the aero-engine turbine, high-temperature structural parts such as turbine blades usually use single-crystal superalloys with excellent high-temperature mechanical properties. The crystal selection method is to nucleate a large amount of molten metal in the seeding section, and then the crystal grains compete with each other in the crystal selector to grow and obtain a single crystal with the preferred orientation. This method is currently widely used in industry, but there is a risk of crystal selection failure, and it is difficult to control the spatial orientation of the grown single crystal. Single crysta...

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Problems solved by technology

However, when the composition difference between the seed crystal alloy and the master alloy is small, when the molten master alloy is in contact with the seed crystal, the heat conduction will cause part of the seed crystal to remelt, and the remelted zone of the seed crystal is likely to produce miscellaneous crystals that are inconsistent with the original orientation, making the single Crystal preparation failure or deviation from intended orientation

Some existing patents use a seed crystal alloy with a large difference in composition from the master alloy to increase the liquidus temperature difference between the two in order to control the formation of the remelting zone, but the matching between the seed crystal and the master alloy decreases accordingly , the driving force of single crystal growth becomes larger, and the degree of supercooling increases, which may cause the molten master alloy to spontaneously nucleate and generate miscellaneous crystals that deviate from the orientation

In addition, the main equipment of the seed crystal method is Bridgmen directional solidification, and the temperature gradient of the equipment is generally lower than 50K / cm. The solidification interface of the prepared single crystal is usually in the form of coarse dendrites, and the distance between dendrites is usually greater than 250 μm. The structure is not dense enough and exists severe microsegregation

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