Aluminum 2024-T351 vs. Silicon

Compare Aluminum 2024-T351 vs. Silicon strength, stiffness, weight and thermal properties.

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Aluminum 2024-T351Wrought

SiliconGrown single crystal

Mechanical
Try it on a partA sample part to run stress or thermal on, free in your browser	Open in LessCAD	Open in LessCAD
Yield strength	324MPasourcetypical, 0.2% offset, .500 in dia specimen	not given (tensile used)
Ultimate tensile strength	469MPasourcetypical	130MPasourcemodulus of rupture (bending fracture stress); brittle, no yield point
Flexural strength	not sourced	130MPasourcemodulus of rupture
Elongation at break	19%sourcetypical, in 4D	not sourced
Young's modulus (stiffness)	73.1GPasourcetypical	131GPasourcetypical (single quoted value of an anisotropic crystal)
Density	2,770kg/m³sourcenominal	2,329kg/m³sourcetypical
Strength to weight	117kN·m/kg2.1x higher	55.8kN·m/kg
Stiffness to weight	26.4MN·m/kg	56.2MN·m/kg2.13x higher
Poisson's ratio	0.33sourcetypical (handbook physical constant), all tempers	0.221sourcetypical
Shear modulus	27.5GPa	53.6GPa1.95x stiffer in shear
Bulk modulus	71.7GPa	78.3GPa
Speed of sound	5,137m/s	7,500m/s
Thermal
Thermal conductivity	120W/m·Ksourcetypical, 20 °C	163W/m·Ksourcetypical at 313 K (40 °C)
Thermal expansion	22.9µm/m·Ksourcetypical, mean 20-100 °C	2.62µm/m·Ksourcetypical at 300 K
100 mm part over a 50 °C swing	115µm growth	13.1µm growth8.74x less
Specific heat	875J/kg·Ksourcetypical, at 100 °C	732J/kg·Ksourcetypical
Heats up and cools (diffusivity)	49.5mm²/s	95.6mm²/s1.93x faster
Thermal shock resistance	15,561W/m	48,095W/m3.09x more resistant
Melting point	502–638°Csourcemelting range	1,412°Csourcetypical
Max service temperature	not sourced	300°Csourceproducer's maximum application temperature (optical components)
Values for	2024-T4/T351, Kaiser Aluminum sheet, coil & plate typical datasheet; Poisson from MIL-HDBK-5J	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 2024-T351 stronger than Silicon?

Aluminum 2024-T351 is stronger: its yield strength is 324 MPa against tensile strength 130 MPa for Silicon (2.49x).

Which is lighter, Aluminum 2024-T351 or Silicon?

Silicon is lighter: 2,329 kg/m³ against 2,770 kg/m³ for Aluminum 2024-T351.

Which is stiffer, Aluminum 2024-T351 or Silicon?

Silicon is stiffer: Young's modulus 131 GPa against 73.1 GPa for Aluminum 2024-T351, so the same part in Silicon deflects less under the same load.

Which is lighter for the same job, Aluminum 2024-T351 or Silicon?

For the same stiffness or strength: Aluminum 2024-T351 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 2024-T351	Silicon
Stiff rod or tie (tension)	2.13x heavier	lighter
Stiff beam (bending)	1.59x heavier	lighter
Stiff panel or plate	44% heavier	lighter
Strong rod or tie	lighter	2.1x heavier
Strong beam	lighter	1.55x heavier
Strong panel or plate	lighter	33% 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 2024-T351 or Silicon?

Silicon conducts heat better: 163 W/m·K against 120 W/m·K for Aluminum 2024-T351.

Which expands less with temperature?

Silicon expands less: 2.62 µm/m·K against 22.9 µm/m·K for Aluminum 2024-T351.

Among 72 materials

Stiffness against density

Strength against density