Scandium and Zirconium Microalloying for Grain Stability during High-Temperature Aluminum Brazing
This Sc/Zr-microalloying technology stabilizes the grain structure of 1xxx-series aluminum alloys during high-temperature brazing at 605 °C. By inhibiting recrystallization and abnormal grain growth, it significantly improves mechanical strength and corrosion resistance for extruded components like multi-port tubes, overcoming common thermal degradation issues in automotive heat exchangers and other industrial applications.
Overview
This technology involves the use of scandium (Sc) and zirconium (Zr) as microalloying elements to improve the thermal stability and mechanical performance of 1xxx-series aluminum alloys. These alloys are frequently used in brazed heat exchangers, where exposure to high temperatures—typically around 605 °C—often triggers recrystallization and abnormal grain growth. These phenomena lead to a significant loss of material strength. By precisely engineering the microstructure with Sc and Zr, the technology prevents these structural failures, allowing components to retain their integrity and strength after high-temperature thermal processing.
Technical specifications
The microalloying process focuses on the formation of Al3(Sc,Zr) precipitates. These precipitates feature an Al3Sc core with a Zr-enriched shell, which provides superior resistance to thermal coarsening compared to scandium alone. Key technical capabilities include:
- Enhanced grain stability: Prevents abnormal grain growth even after high-temperature exposure at 605 °C.
- Improved mechanical properties: Retains higher strength levels post-brazing compared to standard 1xxx alloys.
- Enhanced corrosion resistance: Microalloyed composition contributes to better environmental durability.
- Flexibility in processing: Optimized for extruded thin strips and multi-port tubes, with compatibility for various thermomechanical processing routes.
- Post-braze aging potential: Further strength enhancements can be achieved through specific post-braze aging treatments that promote fine Al3(Sc,Zr) precipitation.
Technology readiness level
The technology has reached a maturity level of 6. Researchers at the Université du Québec à Chicoutimi have validated these findings through systematic lab-scale studies and successful application to extruded multi-port tubes, simulating industrial brazing cycles. These studies demonstrate consistent performance gains across varying compositions of Sc and Zr,...
About Université du Québec à Chicoutimi
Université du Québec à Chicoutimi is a mid-sized public research university serving the Saguenay–Lac-Saint-Jean region, with more than 6,500 students and a francophone, community-oriented character. Its Saguenay campus combines specialized research facilities, the National Research Council of Canada’s Aluminium Technology Centre, and a 25 km² teaching and research forest. Partnership and contract-research processes connect faculty with private, public, and community organizations, while a university entrepreneurship centre supports knowledge transfer, commercialization, and startup creation. Research funding draws from NSERC, SSHRC, CIHR, the Canada Foundation for Innovation, and Québec funding bodies.
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