Multiple Aging Heat Treatment Technology of Niobium-Titanium Superconducting Materials

Time-Affected Heat Treatment Techniques of Ni-Ti Superconducting Materials

Superconducting materials, such as those made of Ni-Ti alloys, are widely utilized in advanced technologies, making them an important part of modern engineering and research. As such, the overall performance of these materials is greatly influenced by the heat treatment they experience. The goal of this paper is to identify the effects of different heat treatments on Ni-Ti superconducting materials, as well as to develop an effective procedure to optimize their chemical and mechanical properties.

Thermal treatments are known to significantly modify the microstructure, mechanical, chemical and electrical characteristics of Ni-Ti based superconducting materials. The particular microstructure, thermal stability and hardness of these materials are dependent on the temperature, duration and type of thermal treatment applied. Different heat treatments can lead to a distinct combination of elements in their microstructure, resulting in unique properties of the material. In the case of Ni-Ti alloys, the heat treatments include annealing, ageing, and stabilization. Each has its own purpose and effects.

The annealing process involves heating of the material to temperatures above the recrystallization temperate of the alloy, followed by controlled cooling. This is done to ensure a homogenous composition and to produce a uniform, fine microstructure. Annealing commonly leads to a significant increase in the elastic modulus, tensile strength and yield strength.

Ageing is used to modify the age-hardening properties of the material and to improve the mechanical characteristics, such as strength and ductility. Ageing involves the aging of Ni-Ti alloys at temperatures slightly lower than the recrystallization temperature. Older Ni-Ti alloys generally show superior mechanical properties in terms of increased yield strength and improved fatigue resistance.

Stabilization is a thermal treatment that consists of heating the material to a temperature slightly higher than the recrystallization temperature, followed by controlled cooling. This process results in an improved electrical conductivity and an increased resistance to oxidation. Stabilization is known to improve the magnetic properties of Ni-Ti alloys, while simultaneously decreasing the microhardness of the material.

Additionally, multiple times-affected heat treatments may be conducted in order to optimize the properties of Ni-Ti based materials. conducting such a process involves heating the material to different temperatures, with coolings in between. Each stage of the cycle results in characteristic microstructural changes that are beneficial for the performance of the material.

Examples of multiple times-affected heat treatments include deformation-invoked crystallization (DRX), solutionizing, annealing and quenching. DRX involves heating the material to a temperature slightly below the recrystallization temperature, followed by a rapid cooling of the material. This heat treatment leads to the formation of an equiaxed grain structure, which enables enhanced ductility and higher yield strength. Solutionizing, on the other hand, includes heating the material to the solutionizing temperature, quenching, and then heating the material again to an annealing temperature. During this process, there is a re-dissolution of the lattice structure due to the elevated temperatures, followed by a rapid cooling. This rapid cooling compresses the lattice structure and leads to a decrease in hardness of the material. Lastly, quenching is used to improve the tensile strength, yield strength, and creep resistance of the alloy.

In conclusion, the performance of Ni-Ti based superconducting materials can be greatly enhanced by subjecting them to various heat treatments. These treatments include annealing, ageing, and stabilization, as well as multiple times-affected treatments such as deformation-related crystallization, solutionizing, annealing and quenching. By strategically manipulating the parameters (such as temperature, time, and cooling rate), it is possible to customize the as-obtained microstructural and mechanical properties of these materials for applications.

Multipass Thermal Treatment of Ni-Ti Superconducting Materials

Ni-Ti superconducting materials have been widely used in high-temperature superconductivity (HTS) applications due to their high critical temperatures and low power losses. To further improve their performance, a multipass thermal treatment process has been developed to optimize their microstructures and thermal stability.

The multipass thermal treatment process involves re-heating the Ni-Ti superconducting material at different temperatures and fordifferent lengths of time. This is done in order to achieve an optimal microstructure, which will improve the performance of the material and its thermal stability.

The first pass of the thermal treatment involves heating the material at a high temperature, typically around 600 °C, for a period of time until the desired microstructure is achieved. After the first pass, the material is re-heated at progressively lower temperatures, usually between 300 and 400 °C, for longer periods of time. At each step, the material is heated and cooled more slowly in order to achieve an even more optimized microstructure.

The multipass thermal treatment process is carried out in an oxygen-free environmentfor safety and to ensure a consistent temperature throughout the process. The temperature and time for each pass are carefully monitored to ensure the best performance from the Ni-Ti superconducting material.

The multipass thermal treatment process can significantly improve the performance of Ni-Ti superconducting materials. It can also help to improve their thermal stability, making them better suited for use in HTS applications. It is an important process for achieving optimal performance from Ni-Ti superconducting materials and should be carried out carefully in order to get the best results.