Study on Microstructure of Nb-Ti Based Alloy by Groove Rolling Process

Area of Science:

• Materials Science
• Superconductivity
• Metallurgy

Background:

• Niobium-titanium (Nb-Ti) alloys are crucial for high-field superconducting magnets due to their high critical magnetic field and supercurrent density at cryogenic temperatures (-283 °C).
• Plastic deformation and thermal exposure can alter the microstructure of Nb-Ti alloys, potentially affecting their superconducting properties.
• Increasing critical current density is essential for miniaturizing superconducting magnets while maintaining magnetic field strength.

Purpose of the Study:

• To investigate the effect of strain amount introduced by groove rolling and subsequent heat treatment on the fraction of the alpha-Ti phase in Nb-Ti alloys.
• To understand how optimizing processing and annealing conditions influences critical current density in superconducting wires.
• To explore the role of alpha-Ti phase precipitation and morphology in enhancing flux pinning and superconducting characteristics.

Main Methods:

• Nb-Ti alloy specimens were subjected to groove rolling at room temperature with varying strain amounts (2.0, 3.16, 4.28, and 5.57).
• Heat treatment was applied to induce uniform precipitation of the alpha-Ti phase.
• Microstructural analysis was conducted using field emission scanning electron microscopy (FESEM) to examine the alpha-Ti phase distribution and morphology.

Main Results:

• The study examined the relationship between strain, heat treatment, and the resulting fraction of the alpha-Ti phase in Nb-Ti alloys.
• Optimized heat treatment leads to uniform precipitation of the non-superconducting alpha-Ti phase within the superconducting Nb-Ti matrix.
• The dispersed alpha-Ti phase acts as effective pinning sites for magnetic flux, thereby improving the critical current density.

Conclusions:

• Uniform precipitation of the alpha-Ti phase through controlled heat treatment is a key strategy for enhancing the critical current density of Nb-Ti superconducting wires.
• The morphology and dispersion of the alpha-Ti phase significantly influence flux pinning and the overall superconducting performance.
• This research provides insights into optimizing fabrication processes for advanced superconducting materials.