Oxidation Behaviour of Microstructurally Highly Metastable Ag-La Alloy

Area of Science:

• Materials Science
• Metallurgy
• Nanotechnology

Background:

• Developing advanced materials for electric contacts is crucial for improving device performance and longevity.
• Silver-based alloys are widely used, but enhancing their properties requires novel compositions and processing.
• Lanthanum (La) addition to silver (Ag) offers potential for unique microstructural development.

Purpose of the Study:

• To investigate a new silver-based alloy containing 2 wt.% lanthanum (La) as a potential electric contact material.
• To characterize the microstructure of the Ag-La alloy after rapid solidification and internal oxidation.
• To understand the mechanisms of internal oxidation in this nanostructured Ag-La system.

Main Methods:

• Rapid solidification using the melt spinning technique to prepare Ag-La alloy ribbons.
• High-temperature internal oxidation to form oxide nanoparticles within the silver matrix.
• Microstructural characterization using Field Emission Scanning Electron Microscopy (FESEM) and Scanning Transmission Electron Microscopy (STEM) with Energy Dispersive X-ray (EDX) analysis.

Main Results:

• Rapid solidification produced a microstructure with fine α_Ag grains and Ag₅La intermetallic particles.
• Internal oxidation resulted in the formation of fine, submicron-sized La₂O₃ oxide nanoparticles dispersed throughout the silver matrix.
• Three distinct mechanisms of internal oxidation were identified, involving La from solid solution and Ag₅La particles.

Conclusions:

• The nanostructured Ag-La₂O₃ material, achieved through rapid solidification and internal oxidation, is a promising candidate for electric contact applications.
• The controlled formation of La₂O₃ nanoparticles enhances the material's microstructure.
• Understanding the internal oxidation mechanisms is key to optimizing the properties of these advanced silver alloys.