Copper C12200 vs. Magnesium AZ31B-H24

Compare Copper C12200 vs. Magnesium AZ31B-H24 strength, stiffness, weight and thermal properties.

Mechanical	Copper C12200	Magnesium AZ31B-H24
Yield strength	69MPa1	220MPa23.19x stronger
Ultimate tensile strength	221MPa1	290MPa231% stronger
Elongation at break	45%13.46x more ductile	13%2
Young's modulus (stiffness)	117GPa12.62x stiffer	44.8GPa3
Density	8,941kg/m³1	1,769kg/m³35.05x lighter
Strength to weight	7.72kN·m/kg	124kN·m/kg16.1x higher
Stiffness to weight	13.1MN·m/kg	25.3MN·m/kg1.93x higher
Poisson's ratio	0.344	0.353
Shear modulus	43.7GPa2.64x stiffer in shear	16.6GPa
Bulk modulus	122GPa2.45x higher	49.8GPa
Speed of sound	3,621m/s	5,032m/s39% faster

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Copper C12200	Magnesium AZ31B-H24
Thermal conductivity	339W/m·K14.41x more heat through a fin	76.9W/m·K2
Thermal expansion	16.9µm/m·K11.59x less	26.8µm/m·K2
100 mm part over a 50 °C swing	84.5µm growth1.59x less	134µm growth
Specific heat	385J/kg·K1	1,040J/kg·K22.7x higher
Heats up and cools (diffusivity)	98.5mm²/s2.36x faster	41.8mm²/s
Thermal shock resistance	7,799W/m	9,159W/m17% more resistant
Melting point	liquidus1,083°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: Copper Development Association, Magnesium Elektron, U.S. Department of Defense, Wieland

Copper C12200: C12200 phosphorus-deoxidized copper (DHP, the air-conditioning and refrigeration tube copper), tube annealed to 0.050 mm grain size (OS050), 0.065 in. wall, copper.org typical 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
C12200 Alloy (copper.org)Copper Development Associationarchived copyCopper C12200 · Yield strength: typical, 0.5% extension under load, 0.065 in. tubeCopper C12200 · Ultimate tensile strength: typical, 0.065 in. tubeCopper C12200 · Elongation at break: typical, 0.065 in. tubeCopper C12200 · Young's modulus (stiffness): typicalCopper C12200 · Density: nominalCopper C12200 · Thermal conductivity: typical, 20 °CCopper C12200 · Thermal expansion: typical, mean 20-100 °CCopper C12200 · Specific heat: typical, 20 °CCopper C12200 · Melting point: liquidus
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
Wieland-K19 (Cu-DHP, C12200) Data SheetWielandarchived copyCopper C12200 · Poisson's ratio: reference value at room temperature (Wieland-K19 = Cu-DHP = C12200, rolled products)

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 Copper C12200 stronger than Magnesium AZ31B-H24?

Magnesium AZ31B-H24 is stronger: its yield strength is 220 MPa against 69 MPa for Copper C12200 (3.19x).

Which is lighter, Copper C12200 or Magnesium AZ31B-H24?

Magnesium AZ31B-H24 is lighter: 1,769 kg/m³ against 8,941 kg/m³ for Copper C12200.

Which is stiffer, Copper C12200 or Magnesium AZ31B-H24?

Copper C12200 is stiffer: Young's modulus 117 GPa against 44.8 GPa for Magnesium AZ31B-H24, so the same part in Copper C12200 deflects less under the same load.

Which is lighter for the same job, Copper C12200 or Magnesium AZ31B-H24?

For the same stiffness or strength: Magnesium AZ31B-H24 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.

Part that must be	Copper C12200	Magnesium AZ31B-H24
Stiff rod or tie (tension)	1.93x heavier	lighter
Stiff beam (bending)	3.12x heavier	lighter
Stiff panel or plate	3.67x heavier	lighter
Strong rod or tie	16.1x heavier	lighter
Strong beam	10.9x heavier	lighter
Strong panel or plate	9.02x 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, Copper C12200 or Magnesium AZ31B-H24?

Copper C12200 stretches further before it breaks: 45% elongation at break against 13% for Magnesium AZ31B-H24.

Thermal

Which conducts heat better, Copper C12200 or Magnesium AZ31B-H24?

Copper C12200 conducts heat better: 339 W/m·K against 76.9 W/m·K for Magnesium AZ31B-H24.

Which expands less with temperature?

Copper C12200 expands less: 16.9 µm/m·K against 26.8 µm/m·K for Magnesium AZ31B-H24.