Segregation in twin-roll cast Mg alloy and its suppression through alloy design

• Segregation in twin-roll cast (TRC) Mg alloy is reduced by modifying alloy system.
• Conventional TRC Mg–3Al–1Zn (AZ31) alloy has severe inverse and central segregation of solute atoms.
• Mg–3Al–1Sn (AT31) alloy has almost no segregation due to its narrow freezing range.
• TRC AT31 alloy has comparable tensile properties to those of TRC AZ31 alloy.

The present study is aimed at reducing the degree of segregation in twin-roll cast (TRC) Mg alloy by the addition of suitable alloying element. It shows that conventional TRC Mg–3Al–1Zn (AZ31) alloy exhibits severe inverse and central segregation of solute Al and Zn atoms due to its rather wide freezing range. The substitution of Zn by Sn effectively reduces the freezing range and no segregation of solutes is found through the thickness of the alloy, Mg–3Al–1Sn (AT31). AT31 alloy also has quite comparable tensile properties to those of TRC AZ31 alloy, making AT31 alloy an ideal alloy for TRC.