Aluminum 5052-H32 vs. Magnesium AZ91D

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

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Mechanical
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Yield strength	195MPasourcetypical, 0.2% offset	150MPasourcetypical, 0.2% tensile yield, ambient temperature
Ultimate tensile strength	230MPasourcetypical	230MPasourcetypical, ambient temperature
Elongation at break	12%sourcetypical	3%sourcetypical, ambient temperature
Young's modulus (stiffness)	70GPasourcetypical1.56x stiffer	45GPasourcetypical
Density	2,685kg/m³sourcenominal	1,810kg/m³sourcetypical
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	0.33sourcetypical (handbook physical constant)	0.35sourcebase material: AZ91C casting (MIL-HDBK-5J handbook physical constant)
Shear modulus	26.3GPa1.58x stiffer in shear	16.7GPa
Bulk modulus	68.6GPa	50GPa
Speed of sound	5,106m/s	4,986m/s
Thermal
Thermal conductivity	138W/m·Ksourcebase material: 5052 in O temper (same alloy, annealed); Kaiser typical	72W/m·Ksourcetypical
Thermal expansion	23.8µm/m·Ksourcetypical, mean 20-100 °C	25µm/m·Ksourcetypical, temperature range not stated
100 mm part over a 50 °C swing	119µm growth5% less	125µm growth
Specific heat	963J/kg·Ksourceat 100 °C (212 °F); table covers O, H32, H34, H36, H38	1,050J/kg·Ksourcetypical
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	605–650°Csourcemelting range	470–595°Csourcemelting range
Values for	5052-H32, Kaiser Aluminum tube & pipe typical datasheet (mechanical, CTE, melting); MIL-HDBK-5J (Poisson, density, specific heat)	ELEKTRON AZ91D magnesium die-casting alloy, as cast; Magnesium Elektron datasheet 475 (7/01), typical properties; Poisson from MIL-HDBK-5J for AZ91C castings.

Every value links to the document that states it. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.

Questions

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 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.

Among 72 materials

Stiffness against density

Strength against density