A Method for Controlling the Growth of Nanocrystalline Texture Using Alternating Ultrasonic Frequency

Abstract

The invention discloses a method for controlling the growth of nanocrystalline texture by using alternating ultrasonic frequency, comprising the following steps: (1) performing Pd-Sn sensitized pre-nucleation on a substrate; (2) placing the substrate in sulfamic acid Electrodeposition is carried out in the nickel plating solution of the nickel system. During the electrodeposition process, the ultrasonic generator I is installed along the horizontal direction of the electrode, and the ultrasonic generator II is installed in the vertical direction; (3) The sample after the electrodeposition is completed in a protective atmosphere Perform aging stabilization heat treatment. This method can promote the local overcooling of the micro-region during the dendrite growth process, triggering more nucleation centers; fragment the dendrites and inhibit the texture-optimized growth trend; make the fragmented dendrites become nucleation centers in other directions, without Produce defects such as whiskers; make Ni crystals grow randomly in multiple directions, making the structure dense, and its Young's modulus E r Up to 198GPa, hardness up to 914HV 0.2 ; The process is simple, the wiring of the ultrasonic generator is flexible, and the operation is convenient.

Description

technical field [0001] The invention relates to a method for growing a nanocrystal texture, more particularly, to a method for regulating the growth of a nanocrystal texture by using alternating ultrasonic frequencies. Background technique [0002] Nickel-based superalloys / coatings have been widely used as high-temperature functional materials in aerospace, 3D printing, and biological bone devices. At present, the traditional DC electrodeposited Ni coating has texture coarsening, and large dendrites cannot be fragmented during the growth process, resulting in obvious texture fold-optimal coarsening and defects such as small-angle grain boundaries. In acidic and other corrosive media, there are Severe pitting tendency. During the high temperature oxidation process, due to the presence of Ni 2+ Cationic holes, external active [O] atoms take advantage of the holes to enter, resulting in oxidation of grain boundaries, making the microstructure of the coating low in density. I...

AI Technical Summary

Problems solved by technology

At present, the traditional DC electrodeposited Ni coating has texture coarsening, and large dendrites cannot be fragmented during the growth process, resulting in obvious texture fold-optimal coarsening and defects such as small-angle grain boundaries. In acidic and other corrosive media, there are severe pitting tendency

During the high temperature oxidation process, due to the presence of Ni 2+ Cationic holes, external active [O] atoms take advantage of the holes to enter, resulting in grain boundary oxidation, making the microstructure of the coating low in density

In recent years, the developed pulse electrodeposition technology uses high peak current density and overpotential to induce high nucleation rate, but in essence, the texture preferential growth trend along the Ni(111) direction of the low-energy close-packed surface does not It is not obviously suppressed, and some coarse dendrites still remain in the Ni coating. At the same time, the instantaneous high overpotential in the pulse electrodeposition promotes the non-spontaneous rapid crystallization, which brings a large number of substructures such as dislocations or crystals, which are not conducive to the thermal conductivity of nanocrystalline Ni. Stability; in order to solve the above problems, many scholars introduced a single direction (single frequency) ultrasonic oscillation field during the pulse electrodeposition process, the texture along the ultrasonic direction was fragmented, the grains were obviously refined, and the grain boundaries were clear , the properties such as hardness and toughness are improved, but the deposition rate is greatly reduced. The dendrites fragmented by ultrasonic waves are not adsorbed to the surface of active growth points to nucleate and add value, but are washed to the electrolysis by the action of ultrasonic micro-jet in a single direction. In the liquid solution, this part of the dendrite is free in the solution, which will easily lead to defects such as whiskers.

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