6061-T6/T651, Kaiser Aluminum typical properties (sheet, coil & plate datasheet); Poisson from MIL-HDBK-5J
Zamak 3 (ASTM B86 die cast), Nathan Trotter (zinc alloy producer) technical data sheet, typical values
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 stronger than Zinc Zamak 3?
Aluminum is stronger: its yield strength is 276 MPa against 221 MPa for Zinc Zamak 3 (25%).
Which is lighter, Aluminum or Zinc Zamak 3?
Aluminum is lighter: 2,700 kg/m³ against 6,600 kg/m³ for Zinc Zamak 3.
Which is stiffer, Aluminum or Zinc Zamak 3?
Zinc Zamak 3 is stiffer: Young's modulus 85.5 GPa against 68.3 GPa for Aluminum, so the same part in Zinc Zamak 3 deflects less under the same load.
Which is lighter for the same job, Aluminum or Zinc Zamak 3?
For the same stiffness or strength: Aluminum 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
Aluminum
Zinc Zamak 3
Stiff rod or tie (tension)
lighter
1.95x heavier
Stiff beam (bending)
lighter
2.18x heavier
Stiff panel or plate
lighter
2.27x heavier
Strong rod or tie
lighter
3.05x heavier
Strong beam
lighter
2.83x heavier
Strong panel or plate
lighter
2.73x 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 or Zinc Zamak 3?
Aluminum conducts heat better: 167 W/m·K against 113 W/m·K for Zinc Zamak 3.
Which expands less with temperature?
Aluminum expands less: 23.6 µm/m·K against 27.4 µm/m·K for Zinc Zamak 3.