Grain refiner breakthrough for magnesium alloys

Dr Hari Babu Nadendla from the Brunel Centres for Advanced Solidification Techniques at Brunel University London
A team of scientists, led by Dr Hari Babu Nadendla from the Brunel Centres for Advanced Solidification Techniques at Brunel University London, claims to have perfected the first ever grain refiner master alloy for magnesium-aluminium alloys.

Dr Nadendla said: “The niobium-based master alloy is shown to be effective in refining aluminium-containing magnesium alloys which are typically processed using sand or high pressure die casting or direct-chill casting. Our research showed significant improvements in both tensile strength and ductility after using the niobium master alloy.

The scientists found that the niobium-based master alloy not only filled the missing gap in grain refiners for magnesium alloys but also offered advantages over titanium in aluminium-silicon alloys which are said to be more widely used.

However this could change thanks to this discovery. The addition of a niobium grain refiner could mean an end to the over-engineering of cast components with potential weight savings of up to 30% with no loss of strength or ductility. In both the automotive and aerospace industries weight reduction is a key driver.

Another benefit of the refiner is that the excess melt from aluminium-silicon process can be recycled

“At the moment it is generally sent off-site for recycling because of iron contamination making it brittle and so requiring specialist treatment,” Dr Nadendla explained. “If the melt is treated with our discovery, excess alloy from a pour or spills and overfills can simply be recycled back into the process.”

Dr Nadendla’s team have has already trialled the master alloy in factory conditions with melts of up to six tonnes. But, they feel they have as yet barely scraped the surface and intend to investigate further in Brunel’s Advanced Metals Casting Centre which aims to plug the gap between laboratory discoveries and commercial production.

Author
Tom Austin-Morgan

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