Aluminum ADC12 vs. Magnesium AZ31B-H24

Compare Aluminum ADC12 vs. Magnesium AZ31B-H24 strength, stiffness, weight and thermal properties.

Mechanical	Aluminum ADC12	Magnesium AZ31B-H24
Yield strength	one test result149MPa1	220MPa248% stronger
Ultimate tensile strength	one test result345MPa119% stronger	290MPa2
Elongation at break	one test result2.3%1	13%25.65x more ductile
Young's modulus (stiffness)	standard value79.8GPa31.78x stiffer	44.8GPa4
Density	measured2,680kg/m³5	1,769kg/m³41.51x lighter
Strength to weight	55.6kN·m/kg	124kN·m/kg2.24x higher
Stiffness to weight	29.8MN·m/kg18% higher	25.3MN·m/kg
Poisson's ratio	not sourced	0.354
Shear modulus	not sourced	16.6GPa
Bulk modulus	not sourced	49.8GPa
Speed of sound	5,457m/s8% faster	5,032m/s

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Aluminum ADC12	Magnesium AZ31B-H24
Thermal conductivity	125W/m·K51.63x more heat through a fin	76.9W/m·K2
Thermal expansion	measured21µm/m·K528% less	26.8µm/m·K2
100 mm part over a 50 °C swing	105µm growth28% less	134µm growth
Specific heat	measured911J/kg·K5	1,040J/kg·K214% higher
Heats up and cools (diffusivity)	51.2mm²/s22% faster	41.8mm²/s
Thermal shock resistance	not sourced	9,159W/m
Melting point	solidus-liquidus515–582°C5	not sourced
Max service temperature	not sourced	149°C4

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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Sources5 documents: Daiki Aluminium Industry, Magnesium Elektron, S.S. Aluminum, U.S. Department of Defense

Aluminum ADC12: JIS ADC12 (Al-Si-Cu, about A383 / EN AC-46100) high-pressure die-casting alloy, as cast; physical properties from Daiki Aluminium Industry (ADC12 ingot producer) measured values; modulus from S.S.Aluminum (ADC12 ingot producer) standard values.
Magnesium AZ31B-H24: AZ31B-H24 sheet 0.016-0.062 in., MIL-HDBK-5J Table 4.2.1.0(b) (AMS 4377); strengths are S-basis MINIMUMS

1
NA Alloys Product DataDaiki Aluminium IndustryAluminum ADC12 · Yield strength: one test result, 0.2% proof stress, as cast, ASTM tensile bar (Daiki)Aluminum ADC12 · Ultimate tensile strength: one test result, as cast, ASTM tensile bar (Daiki)Aluminum ADC12 · Elongation at break: one test result, as cast, ASTM tensile bar (Daiki)
2
Elektron AZ31B Sheet, Plate & Coil (Datasheet 482)Magnesium Elektronarchived copyMagnesium AZ31B-H24 · Yield strength: typical, H24, 0.5-6 mm, 0.2 % proof stressMagnesium AZ31B-H24 · Ultimate tensile strength: typical, H24, 0.5-6 mmMagnesium AZ31B-H24 · Elongation at break: typical, H24, 0.5-6 mm, gauge 5.65√AMagnesium AZ31B-H24 · Thermal conductivity: typical (temper/temperature not stated)Magnesium AZ31B-H24 · Thermal expansion: typical (temperature range not stated)Magnesium AZ31B-H24 · Specific heat: typical
3
Die-Casting Alloys (ダイカスト用合金)S.S. AluminumAluminum ADC12 · Young's modulus (stiffness): standard value (S.S.Aluminum)
4
MIL-HDBK-5J, Metallic Materials and Elements for Aerospace Vehicle Structures (2003)U.S. Department of DefenseMagnesium AZ31B-H24 · Young's modulus (stiffness): typical (handbook physical constant)Magnesium AZ31B-H24 · Density: nominalMagnesium AZ31B-H24 · Poisson's ratio: typical (handbook physical constant)Magnesium AZ31B-H24 · Max service temperature: stated application limit
5
DIK365 Product DataDaiki Aluminium IndustryAluminum ADC12 · Density: measured (Daiki)Aluminum ADC12 · Thermal conductivity: measured on specimens cut from a 50 x 100 x 5 mm flat die casting (Daiki)Aluminum ADC12 · Thermal expansion: measured, temperature range not stated (Daiki)Aluminum ADC12 · Specific heat: measured (Daiki)Aluminum ADC12 · Melting point: solidus-liquidus (Daiki)

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 ADC12 stronger than Magnesium AZ31B-H24?

Magnesium AZ31B-H24 is stronger: its yield strength is 220 MPa against 149 MPa for Aluminum ADC12 (48%).

Which is lighter, Aluminum ADC12 or Magnesium AZ31B-H24?

Magnesium AZ31B-H24 is lighter: 1,769 kg/m³ against 2,680 kg/m³ for Aluminum ADC12.

Which is stiffer, Aluminum ADC12 or Magnesium AZ31B-H24?

Aluminum ADC12 is stiffer: Young's modulus 79.8 GPa against 44.8 GPa for Magnesium AZ31B-H24, so the same part in Aluminum ADC12 deflects less under the same load.

Which is lighter for the same job, Aluminum ADC12 or Magnesium AZ31B-H24?

For the same stiffness or strength: Aluminum ADC12 is lighter for a stiff rod or tie (tension); Magnesium AZ31B-H24 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 ADC12	Magnesium AZ31B-H24
Stiff rod or tie (tension)	lighter	18% heavier
Stiff beam (bending)	14% heavier	lighter
Stiff panel or plate	25% heavier	lighter
Strong rod or tie	2.24x heavier	lighter
Strong beam	1.96x heavier	lighter
Strong panel or plate	1.84x 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 ADC12 or Magnesium AZ31B-H24?

Magnesium AZ31B-H24 stretches further before it breaks: 13% elongation at break against 2.3% for Aluminum ADC12.

Thermal

Which conducts heat better, Aluminum ADC12 or Magnesium AZ31B-H24?

Aluminum ADC12 conducts heat better: 125 W/m·K against 76.9 W/m·K for Magnesium AZ31B-H24.

Which expands less with temperature?

Aluminum ADC12 expands less: 21 µm/m·K against 26.8 µm/m·K for Magnesium AZ31B-H24.