Aluminum 6063-T6 vs. Silicon

Compare Aluminum 6063-T6 vs. Silicon strength, stiffness, weight and thermal properties.

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SiliconGrown single crystal

Mechanical
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Yield strength	215MPasourcetypical, T6, 0.0625 in specimen	not given (tensile used)
Ultimate tensile strength	240MPasourcetypical, T6	130MPasourcemodulus of rupture (bending fracture stress); brittle, no yield point
Flexural strength	not sourced	130MPasourcemodulus of rupture
Elongation at break	12%sourcetypical, T6, in 4D	not sourced
Young's modulus (stiffness)	69GPasourcetypical	131GPasourcetypical (single quoted value of an anisotropic crystal)
Density	2,700kg/m³sourcenominal, 20 °C	2,329kg/m³sourcetypical
Strength to weight	79.6kN·m/kg43% higher	55.8kN·m/kg
Stiffness to weight	25.6MN·m/kg	56.2MN·m/kg2.2x higher
Poisson's ratio	not sourced	0.221sourcetypical
Shear modulus	not sourced	53.6GPa
Bulk modulus	not sourced	78.3GPa
Speed of sound	5,055m/s	7,500m/s
Thermal
Thermal conductivity	201W/m·Ksourcetypical, T6, 20 °C	163W/m·Ksourcetypical at 313 K (40 °C)
Thermal expansion	23.4µm/m·Ksourcetypical, mean 20-100 °C	2.62µm/m·Ksourcetypical at 300 K
100 mm part over a 50 °C swing	117µm growth	13.1µm growth8.93x less
Specific heat	901J/kg·Ksourcetypical, 20 °C (Hydro EN AW-6063)	732J/kg·Ksourcetypical
Heats up and cools (diffusivity)	82.6mm²/s	95.6mm²/s16% faster
Thermal shock resistance	not sourced	48,095W/m
Melting point	615–655°Csourcemelting range	1,412°Csourcetypical
Max service temperature	not sourced	300°Csourceproducer's maximum application temperature (optical components)
Values for	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).	Synthetic single-crystal silicon (cubic, diamond structure), Korth Kristalle (crystal grower) material data; Korth usually supplies Floating Zone (FZ) material, Czochralski (Cz) also offered. Silicon is elastically anisotropic; the producer quotes one modulus and the solver is isotropic.

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 6063-T6 stronger than Silicon?

Aluminum 6063-T6 is stronger: its yield strength is 215 MPa against tensile strength 130 MPa for Silicon (1.65x).

Which is lighter, Aluminum 6063-T6 or Silicon?

Silicon is lighter: 2,329 kg/m³ against 2,700 kg/m³ for Aluminum 6063-T6.

Which is stiffer, Aluminum 6063-T6 or Silicon?

Silicon is stiffer: Young's modulus 131 GPa against 69 GPa for Aluminum 6063-T6, so the same part in Silicon deflects less under the same load.

Which is lighter for the same job, Aluminum 6063-T6 or Silicon?

For the same stiffness or strength: Aluminum 6063-T6 is lighter for a strong rod or tie, strong beam, strong panel or plate; Silicon is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate.

Part that must be	Aluminum 6063-T6	Silicon
Stiff rod or tie (tension)	2.2x heavier	lighter
Stiff beam (bending)	1.6x heavier	lighter
Stiff panel or plate	44% heavier	lighter
Strong rod or tie	lighter	43% heavier
Strong beam	lighter	21% heavier
Strong panel or plate	lighter	11% heavier

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 6063-T6 or Silicon?

Aluminum 6063-T6 conducts heat better: 201 W/m·K against 163 W/m·K for Silicon.

Which expands less with temperature?

Silicon expands less: 2.62 µm/m·K against 23.4 µm/m·K for Aluminum 6063-T6.

Among 72 materials

Stiffness against density

Strength against density