Aluminum 6063-T6 vs. Magnesium AZ31B-H24

Compare Aluminum 6063-T6 vs. Magnesium AZ31B-H24 strength, stiffness, weight and thermal properties.

Mechanical	Aluminum 6063-T6	Magnesium AZ31B-H24
Yield strength	215MPa1	220MPa2
Ultimate tensile strength	240MPa1	290MPa221% stronger
Elongation at break	12%1	13%2
Young's modulus (stiffness)	69GPa11.54x stiffer	44.8GPa3
Density	2,700kg/m³1	1,769kg/m³31.53x lighter
Strength to weight	79.6kN·m/kg	124kN·m/kg1.56x higher
Stiffness to weight	25.6MN·m/kg	25.3MN·m/kg
Poisson's ratio	not sourced	0.353
Shear modulus	not sourced	16.6GPa
Bulk modulus	not sourced	49.8GPa
Speed of sound	5,055m/s	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 6063-T6	Magnesium AZ31B-H24
Thermal conductivity	201W/m·K12.61x more heat through a fin	76.9W/m·K2
Thermal expansion	23.4µm/m·K115% less	26.8µm/m·K2
100 mm part over a 50 °C swing	117µm growth15% less	134µm growth
Specific heat	901J/kg·K4	1,040J/kg·K215% higher
Heats up and cools (diffusivity)	82.6mm²/s1.98x faster	41.8mm²/s
Thermal shock resistance	not sourced	9,159W/m
Melting point	melting range615–655°C1	not sourced
Max service temperature	not sourced	149°C3

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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Sources4 documents: Kaiser Aluminum, Magnesium Elektron, U.S. Department of Defense, Hydro

Aluminum 6063-T6: 6063-T6 extruded tube, Kaiser Aluminum Tube & Pipe Alloy 6063 Technical Data (Rev. 05/06), typical properties; specific heat from Hydro EN AW-6063 extruded-products datasheet (Rev.4, 03/2023).
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
Alloy 6063 Tube & Pipe Technical Data, Rev. 05/06Kaiser Aluminumarchived copyAluminum 6063-T6 · Yield strength: typical, T6, 0.0625 in specimenAluminum 6063-T6 · Ultimate tensile strength: typical, T6Aluminum 6063-T6 · Elongation at break: typical, T6, in 4DAluminum 6063-T6 · Young's modulus (stiffness): typicalAluminum 6063-T6 · Density: nominal, 20 °CAluminum 6063-T6 · Thermal conductivity: typical, T6, 20 °CAluminum 6063-T6 · Thermal expansion: typical, mean 20-100 °CAluminum 6063-T6 · Melting point: melting range
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
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
4
Technical Datasheet, Extruded Products: Alloy EN AW-6063 (Rev. 4, 2023)Hydroarchived copyAluminum 6063-T6 · Specific heat: typical, 20 °C (Hydro EN AW-6063)

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 6063-T6 stronger than Magnesium AZ31B-H24?

Magnesium AZ31B-H24 is stronger: its yield strength is 220 MPa against 215 MPa for Aluminum 6063-T6 (2%).

Which is lighter, Aluminum 6063-T6 or Magnesium AZ31B-H24?

Magnesium AZ31B-H24 is lighter: 1,769 kg/m³ against 2,700 kg/m³ for Aluminum 6063-T6.

Which is stiffer, Aluminum 6063-T6 or Magnesium AZ31B-H24?

Aluminum 6063-T6 is stiffer: Young's modulus 69 GPa against 44.8 GPa for Magnesium AZ31B-H24, so the same part in Aluminum 6063-T6 deflects less under the same load.

Which is lighter for the same job, Aluminum 6063-T6 or Magnesium AZ31B-H24?

For the same stiffness or strength: 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 6063-T6	Magnesium AZ31B-H24
Stiff rod or tie (tension)	about equal	about equal
Stiff beam (bending)	23% heavier	lighter
Stiff panel or plate	32% heavier	lighter
Strong rod or tie	1.56x heavier	lighter
Strong beam	1.55x heavier	lighter
Strong panel or plate	1.54x 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).

Thermal

Which conducts heat better, Aluminum 6063-T6 or Magnesium AZ31B-H24?

Aluminum 6063-T6 conducts heat better: 201 W/m·K against 76.9 W/m·K for Magnesium AZ31B-H24.

Which expands less with temperature?

Aluminum 6063-T6 expands less: 23.4 µm/m·K against 26.8 µm/m·K for Magnesium AZ31B-H24.