# Nuclear Grade (Grade R1) Hafnium

Nuclear grade hafnium is a hafnium alloy. Cited properties are appropriate for the annealed condition. It has a fairly low heat capacity and a moderately high density among alloys in the same category.

The graph bars on the material properties cards below compare nuclear grade hafnium to: hafnium alloys (top), all alloys in the same category (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

## Mechanical Properties

Elastic (Young's, Tensile) Modulus

78 *GPa* 11 *x 10 ^{6} psi*

Elongation at Break

25 *%*

Poisson's Ratio

0.26

Shear Modulus

31 *GPa* 4.5 *x 10 ^{6} psi*

Tensile Strength: Ultimate (UTS)

350 *MPa* 51 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

170 *MPa* 25 *x 10 ^{3} psi*

## Other Material Properties

Density

13 *g/cm ^{3}* 830

*lb/ft*

^{3}Latent Heat of Fusion

130 *J/g*

Specific Heat Capacity

140 *J/kg-K* 0.034 *BTU/lb-°F*

Thermal Expansion

5.9 *µm/m-K*

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

73 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

180 *kJ/m ^{3}*

Stiffness to Weight: Axial

3.3 *points*

Stiffness to Weight: Bending

11 *points*

Strength to Weight: Axial

7.4 *points*

Strength to Weight: Bending

8.4 *points*

Thermal Shock Resistance

55 *points*

## Alloy Composition

Hf | 99.8 to 100 | |

res. | 0 to 0.23 |

All values are % weight. Ranges represent what is permitted under applicable standards.

## Followup Questions

## Further Reading

ASTM B737: Standard Specification for Hot-Rolled and/or Cold-Finished Hafnium Rod and Wire

ASTM B776: Standard Specification for Hafnium and Hafnium Alloy Strip, Sheet, and Plate