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 Silicon stronger than Titanium Ti-6Al-4V?
Titanium Ti-6Al-4V is stronger: its yield strength is 885 MPa against tensile strength 130 MPa for Silicon (6.81x).
Which is lighter, Silicon or Titanium Ti-6Al-4V?
Silicon is lighter: 2,329 kg/m³ against 4,430 kg/m³ for Titanium Ti-6Al-4V.
Which is stiffer, Silicon or Titanium Ti-6Al-4V?
Silicon is stiffer: Young's modulus 131 GPa against 115 GPa for Titanium Ti-6Al-4V, so the same part in Silicon deflects less under the same load.
Which is lighter for the same job, Silicon or Titanium Ti-6Al-4V?
For the same stiffness or strength: Silicon is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate; Titanium Ti-6Al-4V is lighter for a strong rod or tie, strong beam, strong panel or plate.
Part that must be
Silicon
Titanium Ti-6Al-4V
Stiff rod or tie (tension)
lighter
2.18x heavier
Stiff beam (bending)
lighter
2.03x heavier
Stiff panel or plate
lighter
1.99x heavier
Strong rod or tie
3.58x heavier
lighter
Strong beam
1.89x heavier
lighter
Strong panel or plate
37% 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 conducts heat better, Silicon or Titanium Ti-6Al-4V?
Silicon conducts heat better: 163 W/m·K against 6.6 W/m·K for Titanium Ti-6Al-4V.
Which expands less with temperature?
Silicon expands less: 2.62 µm/m·K against 9 µm/m·K for Titanium Ti-6Al-4V.