Aluminum 5052-H32 vs. Magnesium AZ91D

Compare Aluminum 5052-H32 vs. Magnesium AZ91D strength, stiffness, weight and thermal properties.

Mechanical	Aluminum 5052-H32	Magnesium AZ91D
Yield strength	195MPa130% stronger	150MPa2
Ultimate tensile strength	230MPa1	230MPa2
Elongation at break	12%14x more ductile	3%2
Young's modulus (stiffness)	70GPa11.56x stiffer	45GPa2
Density	2,685kg/m³3	1,810kg/m³248% lighter
Strength to weight	72.6kN·m/kg	82.9kN·m/kg14% higher
Stiffness to weight	26.1MN·m/kg5% higher	24.9MN·m/kg
Poisson's ratio	0.333	base material0.353
Shear modulus	26.3GPa1.58x stiffer in shear	16.7GPa
Bulk modulus	68.6GPa37% higher	50GPa
Speed of sound	5,106m/s2% faster	4,986m/s

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Aluminum 5052-H32	Magnesium AZ91D
Thermal conductivity	base material138W/m·K11.92x more heat through a fin	72W/m·K2
Thermal expansion	23.8µm/m·K1	25µm/m·K2
100 mm part over a 50 °C swing	119µm growth5% less	125µm growth
Specific heat	at 100 °C963J/kg·K3	1,050J/kg·K2
Heats up and cools (diffusivity)	53.4mm²/s41% faster	37.9mm²/s
Thermal shock resistance	10,822W/m1.73x more resistant	6,240W/m
Melting point	melting range605–650°C1	melting range470–595°C2

Thermal conductivity against densityHigher and further left: spreads more heat for its weight

Thermal expansion against thermal conductivityLower and further right: warps less when heated

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Sources3 documents: Kaiser Aluminum, Magnesium Elektron, U.S. Department of Defense

Aluminum 5052-H32: 5052-H32, Kaiser Aluminum tube & pipe typical datasheet (mechanical, CTE, melting); MIL-HDBK-5J (Poisson, density, specific heat)
Magnesium AZ91D: ELEKTRON AZ91D magnesium die-casting alloy, as cast; Magnesium Elektron datasheet 475 (7/01), typical properties; Poisson from MIL-HDBK-5J for AZ91C castings.

1
Alloy 5052 Tube & Pipe Technical DataKaiser Aluminumarchived copyAluminum 5052-H32 · Yield strength: typical, 0.2% offsetAluminum 5052-H32 · Ultimate tensile strength: typicalAluminum 5052-H32 · Elongation at break: typicalAluminum 5052-H32 · Young's modulus (stiffness): typicalAluminum 5052-H32 · Thermal conductivity: base material: 5052 in O temper (same alloy, annealed); Kaiser typicalAluminum 5052-H32 · Thermal expansion: typical, mean 20-100 °CAluminum 5052-H32 · Melting point: melting range
2
Elektron Die Casting Alloys (Datasheet 475)Magnesium Elektronarchived copyMagnesium AZ91D · Yield strength: typical, 0.2% tensile yield, ambient temperatureMagnesium AZ91D · Ultimate tensile strength: typical, ambient temperatureMagnesium AZ91D · Elongation at break: typical, ambient temperatureMagnesium AZ91D · Young's modulus (stiffness): typicalMagnesium AZ91D · Density: typicalMagnesium AZ91D · Thermal conductivity: typicalMagnesium AZ91D · Thermal expansion: typical, temperature range not statedMagnesium AZ91D · Specific heat: typicalMagnesium AZ91D · Melting point: melting range
3
MIL-HDBK-5J, Metallic Materials and Elements for Aerospace Vehicle Structures (2003)U.S. Department of DefenseAluminum 5052-H32 · Density: nominalAluminum 5052-H32 · Poisson's ratio: typical (handbook physical constant)Magnesium AZ91D · Poisson's ratio: base material: AZ91C casting (MIL-HDBK-5J handbook physical constant)Aluminum 5052-H32 · Specific heat: at 100 °C (212 °F); table covers O, H32, H34, H36, H38

Each number points to the document that states it, with the exact basis. Values without a number are computed from the sourced ones. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.

Questions

Mechanical

Is Aluminum 5052-H32 stronger than Magnesium AZ91D?

Aluminum 5052-H32 is stronger: its yield strength is 195 MPa against 150 MPa for Magnesium AZ91D (30%).

Which is lighter, Aluminum 5052-H32 or Magnesium AZ91D?

Magnesium AZ91D is lighter: 1,810 kg/m³ against 2,685 kg/m³ for Aluminum 5052-H32.

Which is stiffer, Aluminum 5052-H32 or Magnesium AZ91D?

Aluminum 5052-H32 is stiffer: Young's modulus 70 GPa against 45 GPa for Magnesium AZ91D, so the same part in Aluminum 5052-H32 deflects less under the same load.

Which is lighter for the same job, Aluminum 5052-H32 or Magnesium AZ91D?

For the same stiffness or strength: Aluminum 5052-H32 is lighter for a stiff rod or tie (tension); Magnesium AZ91D is lighter for a stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.

Part that must be	Aluminum 5052-H32	Magnesium AZ91D
Stiff rod or tie (tension)	lighter	5% heavier
Stiff beam (bending)	19% heavier	lighter
Stiff panel or plate	28% heavier	lighter
Strong rod or tie	14% heavier	lighter
Strong beam	25% heavier	lighter
Strong panel or plate	30% heavier	lighter

For the same stiffness or strength, mass scales with density over stiffness (or strength) raised to a power set by how the part is loaded: 1 for a rod in tension, 1/2 for a beam in bending, 1/3 for a panel (the standard material-selection indices).

Which is more ductile, Aluminum 5052-H32 or Magnesium AZ91D?

Aluminum 5052-H32 stretches further before it breaks: 12% elongation at break against 3% for Magnesium AZ91D.

Thermal

Which conducts heat better, Aluminum 5052-H32 or Magnesium AZ91D?

Aluminum 5052-H32 conducts heat better: 138 W/m·K against 72 W/m·K for Magnesium AZ91D.

Which expands less with temperature?

Aluminum 5052-H32 expands less: 23.8 µm/m·K against 25 µm/m·K for Magnesium AZ91D.