Brunel University, London, reports that a research team has found a patented niobium-base master alloy that not only fills the missing gap in grain refiners for magnesium alloys, but also offers significant advantages over titanium in aluminum-silicon alloys.
According to Dr. Hari Babu Nadendla of the Brunel Centres for Advanced Solidification Techniques, “The niobium-base master alloy is effective in refining aluminum-containing magnesium alloys that are typically processed by sand or high pressure die casting or direct-chill casting. Our research shows significant improvements in both tensile strength and ductility after adding the niobium master alloy.
“We were also delighted to discover that that same master alloy shows much greater grain refinement in Al-Si alloys than titanium, and these are much more widely used than Mg-Al alloys. However, this could change quite rapidly as a result of this discovery, especially in aerospace applications.”
For both alloys, the niobium grain refiner could also mean an end to the over-engineering of cast components, resulting in possible weight savings of up to 30% with no loss of strength or ductility.
The new master alloy also enables in-factory recycling of excess aluminum-silicon alloy melt. Today it must be sent off-site because iron contamination makes it brittle, requiring specialist treatment. However, if the melt is treated with the new master alloy, excess alloy can simply be recycled back into the process.
