AZ81A Magnesium vs. ASTM B685 Alloy
AZ81A magnesium belongs to the magnesium alloys classification, while ASTM B685 alloy belongs to the otherwise unclassified metals. There are 17 material properties with values for both materials. Properties with values for just one material (16, in this case) are not shown. Please note that the two materials have significantly dissimilar densities. This means that additional care is required when interpreting the data, because some material properties are based on units of mass, while others are based on units of area or volume.
For each property being compared, the top bar is AZ81A magnesium and the bottom bar is ASTM B685 alloy.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 46 | |
| 120 |
| Poisson's Ratio | 0.29 | |
| 0.37 |
| Shear Modulus, GPa | 18 | |
| 43 |
| Tensile Strength: Ultimate (UTS), MPa | 160 to 240 | |
| 660 to 1060 |
Thermal Properties
| Latent Heat of Fusion, J/g | 350 | |
| 180 |
| Melting Completion (Liquidus), °C | 600 | |
| 1230 |
| Melting Onset (Solidus), °C | 500 | |
| 1200 |
| Specific Heat Capacity, J/kg-K | 990 | |
| 300 |
| Thermal Expansion, µm/m-K | 27 | |
| 14 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 12 | |
| 5.0 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 65 | |
| 4.1 |
Otherwise Unclassified Properties
| Density, g/cm3 | 1.7 | |
| 11 |
Common Calculations
| Stiffness to Weight: Axial, points | 15 | |
| 6.1 |
| Stiffness to Weight: Bending, points | 70 | |
| 15 |
| Strength to Weight: Axial, points | 26 to 39 | |
| 17 to 27 |
| Strength to Weight: Bending, points | 38 to 50 | |
| 16 to 21 |
| Thermal Shock Resistance, points | 9.1 to 14 | |
| 28 to 46 |
Alloy Composition
| Aluminum (Al), % | 7.0 to 8.1 | |
| 0 to 0.0050 |
| Cadmium (Cd), % | 0 | |
| 0 to 0.050 |
| Copper (Cu), % | 0 to 0.1 | |
| 39.5 to 40.5 |
| Iron (Fe), % | 0 | |
| 0 to 0.050 |
| Lead (Pb), % | 0 | |
| 0 to 0.030 |
| Magnesium (Mg), % | 89.8 to 92.5 | |
| 0 |
| Manganese (Mn), % | 0.13 to 0.35 | |
| 0 |
| Nickel (Ni), % | 0 to 0.010 | |
| 0 |
| Palladium (Pd), % | 0 | |
| 59 to 60.5 |
| Silicon (Si), % | 0 to 0.3 | |
| 0 |
| Silver (Ag), % | 0 | |
| 0 to 0.1 |
| Zinc (Zn), % | 0.4 to 1.0 | |
| 0 to 0.060 |
| Residuals, % | 0 | |
| 0 to 0.2 |