Elemental Composition of Aluminum and Titanium
Aluminum contains silicon, magnesium, zinc, manganese, copper, chromium, and iron, delivering high thermal conductivity and low density. Titanium incorporates hydrogen, nitrogen, oxygen, iron, carbon, and nickel, offering superior strength and biocompatibility despite higher density. The composition differences make titanium stronger but heavier, while aluminum has a lower melting point and higher thermal expansion suitable for heat applications.
Electrical and Thermal Conductivity
Aluminum demonstrates thermal conductivity of 210 W/m-K, significantly outperforming titanium's 17.0 W/m-K. Aluminum exhibits 64% of copper's conductivity, making it suitable for electrical applications, while titanium's minimal electrical conductivity restricts its use in conductive applications. Aluminum maintains consistent conductivity across temperature ranges, whereas titanium's conductivity decreases with heat.
Weight Differences
| Property | Aluminum | Titanium |
|---|---|---|
| Density (g/cm3) | 2.7 | 4.5 |
| Strength-to-weight ratio (kN-m/kg) | 158 | 187 |
| Hardness (Brinell scale) | 245 | 716 |
Aluminum is approximately 66% lighter than titanium, though titanium offers superior strength and hardness for demanding applications.
Corrosion Resistance
Aluminum develops a protective oxide layer naturally and benefits from anodizing or chromate conversion treatments. Titanium demonstrates exceptional corrosion resistance against chloride ions through a stable oxide film, making it ideal for marine and aerospace environments. Galvanic corrosion may occur when these metals contact each other but can be mitigated through isolation or coating.
Machinability
Aluminum displays superior surface finish smoothness due to lower hardness and reduced friction during machining. Titanium causes greater tool wear due to higher hardness and strength. Aluminum forms long, stringy chips allowing higher cutting speeds, while titanium produces shorter, more manageable chips requiring adjusted machining parameters.
Cost Implications
- Cost comparison: titanium costs up to ten times more than aluminum due to superior material properties.
- Manufacturing: titanium's difficult machinability increases production costs, though its strength-to-weight ratio may offset expenses in transportation and assembly.
- Environmental impact: aluminum production is more energy-intensive than titanium production.
