Lead-freeSafe Magnesium AdditionBrittle for Easy PortioningReduced Burn-OffRapid Dissolution
Al-Mg master alloy (50% Al, 50% Mg) for safe, precise magnesium additions to 5xxx and 7xxx series aluminum melts. Brittle, easy to portion. 2"-1/4" lumps.
50/50 Magnesium Aluminum is a master alloy with a nominal composition of 50% Al and 50% Mg, designed for the safe and precise addition of magnesium to aluminum foundry melts. Solidus is approximately 842°F (450°C) and liquidus approximately 870°F (465°C), with a density of 0.080 lbs/in³ (2.22 g/cm³). Unlike pure magnesium ingots, this alloy is extremely brittle due to the high volume fraction of Mg2Al3 intermetallic phases, allowing it to be easily fractured for exact weight adjustments. Its density is closer to liquid aluminum than pure magnesium, promoting rapid mixing and reducing magnesium burn-off on the melt surface. Dissolution is excellent at 1,250°F and above.
This master alloy is specifically formulated for 5000-series and 7000-series aluminum alloys where precise magnesium additions are critical to achieving target chemistry. The brittle character that makes it easy to break and portion also makes it far safer to handle than pure magnesium, which requires special cutting equipment and presents a fire risk. Reduced burn-off compared to pure magnesium additions improves chemistry control and reduces alloy cost.
Supplied as 2″–1/4″ lumps for flexible dosing across furnace heat sizes.
Available Forms
2"-1/4" Lumps
Product Code
6501B
Technical Info
Thermal Properties
Melting Point (Solidus)842°F (450°C)
Melting Point (Liquidus)870°F (466°C)
Physical Properties
Density (imperial)0.08 lbs/in³
Density (metric)2.22 g/cm³
Primary ElementsAl · Mg
Lead FreeYes
Key Features
Safe Magnesium AdditionBrittle for Easy PortioningReduced Burn-OffRapid Dissolution
Solubility Note
Excellent dissolution in molten aluminum at 1,250°F and above.
Nominal Composition
50% Al
50% Mg
Frequently Asked Questions
Common technical inquiries regarding 50/50 Magnesium Aluminum
Pure magnesium ingot is difficult to section accurately, presents a fire risk when cut or exposed to moisture, and has a density significantly lower than liquid aluminum causing it to float and oxidize rapidly on the melt surface before dissolving. The 50/50 master alloy is brittle and easily broken to exact weight, has a density closer to the melt which aids submersion and dissolution, and its pre-alloyed aluminum matrix dramatically reduces the oxidation rate compared to pure magnesium, improving recovery and chemistry control.
When pure magnesium is added to an aluminum melt, it tends to float due to its low density and oxidize rapidly at the melt surface, forming MgO dross and causing significant metal loss before the magnesium dissolves. The 50/50 master alloy's higher density allows it to sink below the surface more readily, exposing less surface area to atmospheric oxidation during dissolution. The aluminum matrix also slows the oxidation kinetics of the magnesium content, giving it more time to dissolve before oxidizing.
Lumps should be preheated to remove surface moisture before charging — cold or damp pieces can cause hydrogen pickup and steam-related spatter. They should be plunged below the melt surface using a bell plunger or similar tool rather than being dropped onto the surface, which maximizes dissolution before exposure to air. Adding in small increments rather than a single large charge also reduces the instantaneous oxidation load on the melt surface and improves overall magnesium recovery.
Al-Be master alloy (97.5% Al, 2.5% Be) for oxidation control and dross reduction in aluminum and magnesium casting melts. 4-5 oz pieces and 5 lb slabs.
Concentrated Al-Be master alloy (95% Al, 5% Be) for oxidation control in large-scale aluminum and magnesium casting. Higher potency than 2.5% grade. 4-5 oz pieces and 5 lb slabs.
Al-Si master alloy (50% Al, 50% Si) for precise silicon additions to improve fluidity and reduce shrinkage in aluminum casting alloys. Waffle and granular forms.
