AZ91D Magnesium vs. R30021 Cobalt
AZ91D magnesium belongs to the magnesium alloys classification, while R30021 cobalt belongs to the cobalt alloys. There are 28 material properties with values for both materials. Properties with values for just one material (7, 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 AZ91D magnesium and the bottom bar is R30021 cobalt.
Metric UnitsUS Customary Units
Mechanical Properties
| Compressive (Crushing) Strength, MPa | 310 to 430 | |
| 1300 |
| Elastic (Young's, Tensile) Modulus, GPa | 46 | |
| 220 |
| Elongation at Break, % | 2.3 to 4.5 | |
| 9.0 |
| Fatigue Strength, MPa | 74 to 85 | |
| 250 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 18 | |
| 86 |
| Tensile Strength: Ultimate (UTS), MPa | 160 to 220 | |
| 700 |
| Tensile Strength: Yield (Proof), MPa | 80 to 130 | |
| 500 |
Thermal Properties
| Latent Heat of Fusion, J/g | 350 | |
| 330 |
| Melting Completion (Liquidus), °C | 600 | |
| 1350 |
| Melting Onset (Solidus), °C | 490 | |
| 1190 |
| Specific Heat Capacity, J/kg-K | 990 | |
| 450 |
| Thermal Conductivity, W/m-K | 78 | |
| 15 |
| Thermal Expansion, µm/m-K | 27 | |
| 11 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 11 | |
| 1.9 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 58 | |
| 2.1 |
Otherwise Unclassified Properties
| Density, g/cm3 | 1.7 | |
| 8.4 |
| Embodied Carbon, kg CO2/kg material | 22 | |
| 8.0 |
| Embodied Energy, MJ/kg | 160 | |
| 110 |
| Embodied Water, L/kg | 990 | |
| 520 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 4.2 to 7.7 | |
| 57 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 69 to 170 | |
| 570 |
| Stiffness to Weight: Axial, points | 15 | |
| 15 |
| Stiffness to Weight: Bending, points | 69 | |
| 24 |
| Strength to Weight: Axial, points | 26 to 34 | |
| 23 |
| Strength to Weight: Bending, points | 38 to 46 | |
| 21 |
| Thermal Diffusivity, mm2/s | 45 | |
| 3.8 |
| Thermal Shock Resistance, points | 9.5 to 13 | |
| 21 |
Alloy Composition
| Aluminum (Al), % | 8.3 to 9.7 | |
| 0 |
| Carbon (C), % | 0 | |
| 0.2 to 0.35 |
| Chromium (Cr), % | 0 | |
| 26 to 29 |
| Cobalt (Co), % | 0 | |
| 61.7 to 67.3 |
| Copper (Cu), % | 0 to 0.030 | |
| 0 |
| Iron (Fe), % | 0 to 0.0050 | |
| 0 to 3.0 |
| Magnesium (Mg), % | 88.7 to 91.2 | |
| 0 |
| Manganese (Mn), % | 0.15 to 0.5 | |
| 0 |
| Molybdenum (Mo), % | 0 | |
| 4.5 to 6.0 |
| Nickel (Ni), % | 0 to 0.0020 | |
| 2.0 to 3.0 |
| Silicon (Si), % | 0 to 0.1 | |
| 0 to 1.5 |
| Zinc (Zn), % | 0.35 to 1.0 | |
| 0 |